He momo toka mura te karāneti i keria mō tōna kaha nui, tōna matotoru, tōna roa, me tōna ātete ki te waikura. Engari he maha ngā whakamahinga o te karāneti – ehara i te mea mō ngā tapawhā me ngā tapawhā rite anake! Inaa, ka mahi tahi mātou me ngā wāhanga karāneti i hangaia i roto i ngā āhua, ngā koki, me ngā pihi o ngā momo rerekētanga katoa i ia wā – me ngā hua tino pai.
Through our state of the art processing, cut surfaces can be exceptionally flat. These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components. Granite is:
■ ka taea te miihini
■ tino papatahi ina tapahia, ina oti hoki
■ ātete ki te waikura
■ pakari
■ roa te mau
He ngāwari hoki te horoi i ngā wāhanga o te karāneti. I te wā e hanga ana i ngā hoahoa ritenga, kia tino whiriwhiria te karāneti mō ōna painga nui.

NGĀ PAEREWA / NGĀ TONO KAKAHU TINO PAI
He nui te ihirangi quartz o te karāhe e whakamahia ana e ZHHIMG mō ā mātou hua pereti mata paerewa, ā, he nui ake te ātete ki te kakahu me te pakaru. He iti te mimiti wai o ā mātou tae Pango Pai rawa atu, ā, ka whakaitihia te tūponotanga o te waikura o ō ine tika i te wā e whakatakotoria ana ki runga i ngā pereti. Ko ngā tae o te karāhe e tukuna ana e ZHHIMG ka iti ake te kanapa, ko te tikanga he iti ake te ngenge o ngā kanohi mō te hunga e whakamahi ana i ngā pereti. Kua whiriwhiria e mātou ā mātou momo karāhe me te whakaaro ki te whakawhānui wera kia iti ai tēnei āhuatanga.

CUSTOM APPLICATIONS
Mēnā ka hiahiatia he pereti me ngā āhua ritenga, he whakaurunga miro, he mokowā, he mīhini rānei, me whiriwhiri koe i tētahi rauemi pēnei i te Black Jinan Black. He tino pakari tēnei rauemi taiao, he pai te aukati i te wiri, ā, he pai ake te ngāwari ki te mīhini.

He mea nui kia mōhiotia ko te tae anake ehara i te tohu mō ngā āhuatanga ā-tinana o te kōhatu. I te nuinga o te wā, he hononga tika te tae o te karāhe ki te aroaro, te ngaro rānei o ngā kohuke, ā, kāore pea he pānga ki ngā āhuatanga e hanga ana i te rauemi pereti mata pai. He karāhe māwhero, hina, me te mangu e tino pai ana mō ngā pereti mata, tae atu ki ngā karāhe mangu, hina, me te māwhero kāore e tino pai mō ngā tono tika. Ko ngā āhuatanga matua o te karāhe, e pā ana ki tōna whakamahinga hei rauemi pereti mata, kāore he pānga ki te tae, ā, ko ēnei e whai ake nei:
■ Te pakari (te piko i raro i te kawenga - e tohuhia ana e te Modulus of Elasticity)
■ Te pakeketanga
■ Te Matotoru
■ Ātete ki te kakahu
■ Te pumau
■ Te Pūngao

He maha ngā rauemi karāhe kua whakamatauria e mātou, ā, kua whakaritea ēnei rauemi. Hei whakamutunga, ko te hua, ko te karāhe pango o Jinan te rauemi pai rawa atu kua mōhiotia e mātou. He rite te karāhe pango o Īnia me te karāhe o Āwherika ki te Tonga ki te karāhe pango o Jinan, engari he iti ake ō rāua āhuatanga ā-tinana i te karāhe pango o Jinan. Ka rapu tonu a ZHHIMG i ētahi atu rauemi karāhe i te ao, ā, ka whakaritea ō rāua āhuatanga ā-tinana.

Mō ētahi atu kōrero mō te karāhe e tika ana mō tāu kaupapa, whakapā mai ki a mātouinfo@zhhimg.com.

He rerekē ngā paerewa e whakamahia ana e ngā kaihanga rerekē. He maha ngā paerewa o te ao.
Ko te Paerewa DIN, ASME B89.3.7-2013, te Whakatakotoranga ā-Motu rānei GGG-P-463c (Ngā Pereti Mata Granite) me ērā atu mea hei pūtake mō ā rātou whakaritenga.

Ā, ka taea e mātou te hanga pereti tirotiro tino tika mō te karāhe kia rite ki ō hiahia. Nau mai whakapiri mai ki a mātou mēnā kei te hiahia koe ki te mōhio atu mō ētahi atu paerewa.

Ka taea te whakaaro ko te papatahi ko ngā pūwāhi katoa o te mata e noho ana i roto i ngā papa e rua e whakarara ana, te papa turanga me te papa tuanui. Ko te ine i te tawhiti i waenga i ngā papa ko te papatahi whānui o te mata. He maha ngā wā ka whai mana tēnei ine papatahi, ā, ka uru pea he tohu taumata.

Hei tauira, ko ngā ātete papatahi mō ngā tohu paerewa e toru kua tautuhia i roto i te whakatakotoranga ā-motu e ai ki te tātai e whai ake nei:
■ Tauira Taiwhanga AA = (40 + tapawhā whakarara/25) x .000001" (taha kotahi)
■ Tau Arowhai A = Tau Taiwhanga AA x 2
■ Taumata Rūma Taputapu B = Taumata Taiwhanga AA x 4.

Mō ngā pereti mata rahi paerewa, ka oati mātou i ngā ātete papatahi e hipa ana i ngā whakaritenga o tēnei whakatakotoranga. Haunga te papatahi, ka aro atu a ASME B89.3.7-2013 me te Whakatakotoranga ā-Motu GGG-P-463c ki ngā kaupapa tae atu ki: te tika o te ine auau, ngā āhuatanga rauemi o ngā karāhe pereti mata, te whakaotinga mata, te taunga o te pūwāhi tautoko, te pakari, ngā tikanga tirotiro e whakaaetia ana, te tāutanga o ngā whakaurunga miro, me ētahi atu.

E tutuki ana, e hipa ana rānei ngā pereti mata karāhe ZHHIMG me ngā pereti tirotiro karāhe i ngā whakaritenga katoa kua whakatakotoria i roto i tēnei whakatakotoranga. I tēnei wā, kāore he whakatakotoranga tautuhi mō ngā pereti koki karāhe, ngā whakarara, ngā tapawhā matua rānei.

Ā, ka kitea e koe ngā tātai mō ētahi atu paerewa i roto iTIKIAKE.

Tuatahi, he mea nui kia noho ma te pereti. Ko te puehu whakakoi e rere ana i te hau te pūtake nui o te pakaru me te haehae o te pereti, nā te mea ka uru ki roto i ngā wahi mahi me ngā mata pa o ngā ine. Tuarua, taupokina tō pereti hei tiaki i a ia mai i te puehu me te kino. Ka taea te whakaroa i te roa o te pakaru mā te hipoki i te pereti ina kore e whakamahia, mā te huri i te pereti i ia wā kia kore ai e nui te whakamahinga o tētahi wāhi, me te whakakapi i ngā papa pa rino i runga i te ine ki ngā papa carbide. Waihoki, kaua e whakatakoto kai, inu ngohengohe rānei ki runga i te pereti. Kia mahara he maha ngā inu ngohengohe kei roto he waikawa waro, he waikawa phosphoric rānei, ka taea te whakarewa i ngā kohuke ngohengohe ka waiho he poka iti ki te mata.

Kei te āhua o te whakamahinga o te pereti tēnei. Mēnā ka taea, ka tūtohu mātou kia horoia te pereti i te tīmatanga o te rā (i te huringa mahi rānei) ā, i te mutunga anō. Mēnā ka paru te pereti, inā koa he wai hinuhinu, he wai piri rānei, me horoi tonu pea.

Horoia te pereti i ia wā ki te wai, ki te horoi pereti mata kore wai rānei a ZHHIMG. He mea nui te whiriwhiri i ngā otinga horoi. Mena ka whakamahia he whakarewa pūngāwerewere (acetone, te whakarewa whakahinuhinu, te waipiro, me ētahi atu), ka whakamatao te mata i te mimiti, ka whakapohehe. I tēnei wā, me tuku kia rite te āhua o te pereti i mua i te whakamahinga, ki te kore ka puta he hapa ine.

Ka rerekē te roa o te wā e hiahiatia ana kia taurite te pereti i runga i te rahi o te pereti, me te nui o te whakamatao. Me rawaka te kotahi hāora mō ngā pereti iti. E rua pea hāora mō ngā pereti nunui. Mena ka whakamahia he kaihoroi wai, ka mimiti hoki te wai.

Ka pupuri hoki te pereti i te wai, ā, ka waikura pea ngā wāhanga whakarewa e pā ana ki te mata. Ka waiho hoki e ētahi kaihoroi he toenga piri i muri i te maroke, ka kukume mai i te puehu ki te hau, ā, ka nui ake te pakaru, kaua e whakaiti.

Kei te whakamahinga o te pereti me te taiao tēnei. Ka tūtohu mātou kia whakahoutia katoatia te pereti hou, te taputapu kēneti tika rānei i roto i te tau kotahi o te hoko. Mena ka whakamahia nuitia te mata o te pereti kēneti, he mea tika kia whakapotohia tēnei wā ki te ono marama. Mā te tirotiro ā-marama mō ngā hapa ine auau mā te whakamahi i te taumata hiko, i tētahi taputapu rite rānei, ka whakaatuhia ngā wāhi pakaru e whanake ana, ā, he torutoru meneti noa iho te roa o te mahi. Kia whakatauhia ngā hua o te whakatikatika tuatahi, ka taea te whakaroa, te whakapoto rānei i te wā whakatikatika e whakaaetia ana, e hiahiatia ana rānei e tō pūnaha kounga ā-roto.

Ka taea e mātou te tuku ratonga hei āwhina i a koe ki te tirotiro me te whakatikatika i tō pereti mata karāhe.

He maha ngā take pea mō ngā rerekētanga i waenga i ngā whakatikatika:

• I horoia te mata ki te wai wera, ki te wai matao rānei i mua i te whakatikatika, ā, kāore i tukuna he wā nui ki te whakataurite.
• Kāore i te tautokona tika te pereti
• Huringa pāmahana
• Ngā tauira
• Te hihi tika o te rā, te wera rānei i runga i te mata o te pereti. Kia tino mohio kei wera te mata i te rama o runga.
• Ngā rerekētanga o te pikinga pāmahana poutū i waenga i te takurua me te raumati (Mēnā ka taea, kia mōhio ki te pāmahana pikinga poutū i te wā e mahia ana te whakatikatika.)
• Kāore i te rawaka te wā i tukuna ki te pereti hei whakataurite i muri i te tukunga
• Te whakamahinga hē o ngā taputapu tirotiro, te whakamahinga rānei o ngā taputapu kāore i te whakatikatikaina
• Te huringa o te mata i puta mai i te kakahu

E hia ngā momo kōhao i runga i te kōhatu karāhe tino tika?

Ngā Mokowā i runga i ngā Wāhanga Granite Tika

Mō te maha o ngā wheketere, ngā rūma tirotiro me ngā taiwhanga, ka whakawhirinakihia ngā pereti mata karāhe tino tika hei pūtake mō te ine tika. Nā te mea ko ia inenga rārangi e whakawhirinaki ana ki tētahi mata tohutoro tika e tangohia mai ai ngā inenga whakamutunga, ka whakaratohia e ngā pereti mata te papa tohutoro pai rawa atu mō te tirotiro mahi me te tahora i mua i te miihini. He turanga pai hoki ēnei mō te ine i te teitei me te ine i ngā mata. Hei tāpiri, nā te papatahi teitei, te pumau, te kounga whānui me te mahi toi ka pai ai te whakamahi mō te whakairi i ngā pūnaha ine mīhini, hiko me te whatu matatau. Mō tētahi o ēnei tukanga ine, he mea nui kia mau tonu te whakatikatika o ngā pereti mata.

Repeat Measurements and Flatness

He mea nui te ine papatahi me te ine auau kia tika ai te mata. Ka taea te whakaaro ko te papatahi ko ngā pūwāhi katoa o te mata kei roto i ngā papa e rua e whakarara ana, te papa turanga me te papa tuanui. Ko te ine i te tawhiti i waenga i ngā papa ko te papatahi whānui o te mata. He maha ngā wā ka whai mana tēnei ine papatahi, ā, ka uru pea he tohu taumata.

The flatness tolerances for three standard grades are defined in the federal specification as determined by the following formula:

Paerewa DIN, Paerewa GB, Paerewa ASME, paerewa JJS... rerekē whenua, rerekē tūnga...

He kōrero anō mō ​​te paerewa.

In addition to flatness, repeatability must be ensured. A repeat measurement is a measurement of local flatness areas. It is a measurement taken anywhere on the surface of a plate that will repeat within the stated tolerance. Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.

Hei whakarite kia tutuki i te pereti mata ngā whakaritenga ine papatahi me te ine auau, me whakamahi ngā kaihanga o ngā pereti mata karāhe i te Federal Specification GGG-P-463c hei pūtake mō ā rātou whakaritenga. E aro ana tēnei paerewa ki te tika o te ine auau, ngā āhuatanga rauemi o te karāhe pereti mata, te whakaotinga mata, te taunga o te pūwāhi tautoko, te pakari, ngā tikanga tirotiro e whakaaetia ana, me te tāutanga o ngā whakaurunga miro.

Checking Plate Accuracy

Mā te whai i ētahi aratohu māmā, ka roa te haumitanga ki tētahi pereti mata karāhe mō ngā tau maha. I runga i te whakamahinga o te pereti, te taiao o te toa me te tika e hiahiatia ana, ka rerekē te auau o te tirotiro i te tika o te pereti mata. Ko te ture whānui ko te whakatikatika katoa o tētahi pereti hou i roto i te tau kotahi o te hoko. Mēnā he maha ngā whakamahinga o te pereti, he mea tika kia whakapotohia tēnei wā ki te ono marama.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

An effective inspection program should include regular checks with an autocollimator, providing actual calibration of overall flatness traceable to National Institute of Standards and Technology (NIST). Comprehensive calibration by the manufacturer or an independent company is necessary from time to time.

Variations Between Calibrations

I ētahi wā, he rerekētanga kei waenga i ngā whakatikatika pereti mata. I ētahi wā, ko ngā āhuatanga pēnei i te huringa o te mata nā te kakahu, te whakamahinga hē o ngā taputapu tirotiro, te whakamahinga rānei o ngā taputapu kāore i whakatikatikaina ka puta ai ēnei rerekētanga. Heoi, ko ngā āhuatanga e rua e tino kitea ana ko te pāmahana me te tautoko.

One of the most important variables is temperature. For instance, the surface might have been washed with a hot or cold solution prior to calibration and not allowed sufficient time to normalize. Other causes of temperature change include drafts of cold or hot air, direct sunlight, overhead lighting or other sources of radiant heat on the surface of the plate.

There also can be variations in the vertical temperature gradient between winter and summer. In some cases, the plate is not allowed sufficient time to normalize after shipment. It is a good idea to record the vertical gradient temperature at the time the calibration is performed.

Another common cause for calibration variation is a plate that is improperly supported. A surface plate should be supported at three points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered.

Only three points can rest solidly on anything but a precision surface. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same three points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. Consider using steel stands with support beams designed to line up with the proper support points. Stands for this purpose are generally available from the surface plate manufacturer.

If the plate is properly supported, precise leveling is only necessary if an application specifies it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

Extend Plate Life

Mā te whai i ētahi aratohu ka whakaiti i te pakaru o te pereti mata karāhe, ā, ka roa ake tōna ora.

Tuatahi, he mea nui kia noho ma te pereti. Ko te puehu whakakoi e rere ana i te hau te tino pūtake o te pakaru me te haehae o te pereti, nā te mea ka piri ki roto i ngā mea mahi me ngā mata pa o ngā ine.

It also is important to cover plates to protect it from dust and damage. Wear life can be extended by covering the plate when not in use.

Hurihia te pereti i ia wā, kia kore ai e whakamahia nuitia tetahi wāhi. Me whakakapi hoki ngā papa whakapā maitai i runga i te ine ki ngā papa karāhe.

Avoid setting food or soft drinks on the plate. Many soft drinks contain either carbonic or phosphoric acid, which can dissolve the softer minerals and leave small pits in the surface.

Where to Relap

Ina hiahiatia he whakahou i te mata o te pereti karāhe, whakaarohia mēnā me mahi tēnei ratonga i te wāhi mahi, i te wāhi whakatikatika rānei. He pai ake te whakahou i te pereti i te wheketere, i tētahi wāhi mahi motuhake rānei. Heoi, ki te kore te pereti i tino pakaru, i roto i te 0.001 inihi o te ātete e hiahiatia ana, ka taea te whakahou i te mata i te wāhi mahi. Ki te pakaru te pereti ki te wāhi neke atu i te 0.001 inihi i waho o te ātete, ki te kino rānei te poka, te pakaru rānei, me tuku ki te wheketere kia hurihia i mua i te whakahou.

A calibration facility has the equipment and factory setting providing the optimum conditions for proper plate calibration and rework if necessary.

Me tino tupato te whiriwhiri i tētahi tohunga whakatikatika me te whakahou papa i te papaanga. Pātai atu mō te whakamanatanga, me te manatoko kei a ia ngā taputapu ka whakamahia e ia he whakatikatika ka taea te whai. He mea nui anō hoki te wheako, nā te mea he maha ngā tau e pau ana ki te ako me pēhea te whakamahi tika i te karāhe tino tika.

Critical measurements start with a precision granite surface plate as a baseline. By ensuring a reliable reference by using a properly calibrated surface plate, manufacturers have one of the essential tools for reliable measurements and better quality parts.Q

Checklist for Calibration Variations

1. I horoia te mata ki te wai wera, ki te wai matao rānei i mua i te whakatikatika, ā, kāore i tukuna he wā nui ki te whakataurite.

2. Kāore i te tika te tautoko o te pereti.

3. Te huringa o te pāmahana.

4. Ngā tauira.

5. Te whitinga o te rā tika, te wera rānei i runga i te mata o te pereti. Kia tino mohio kei wera te mata i te rama o runga.

6. Ngā rerekētanga o te pikinga pāmahana poutū i waenga i te takurua me te raumati. Mena ka taea, kia mōhio ki te pāmahana pikinga poutū i te wā e mahia ana te whakatikatika.

7. Kāore i te rawaka te wā i tukuna ki te pereti hei whakarite i tōna āhua i muri i te tukunga.

8. Te whakamahinga hē o ngā taputapu tirotiro, te whakamahinga rānei o ngā taputapu kāore i whakatikatikaina.

9. Te panonitanga o te mata i puta mai i te kakahu.

Tech Tips

• Nā te mea ko ia inenga rārangi e whakawhirinaki ana ki tētahi mata tohutoro tika e tangohia mai ai ngā inenga whakamutunga, ko ngā pereti mata te papa tohutoro pai rawa atu mō te tirotiro mahi me te tahora i mua i te miihini.
• Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.
• Me uru ki roto i tētahi kaupapa tirotiro whai hua ngā tirotiro auau me tētahi autocollimator, kia tika ai te whakataurite o te papatahi whānui kia taea ai te whai atu ki te Mana Tirotiro ā-Motu.

I roto i ngā matūriki kohuke e hanga ana i te karāneti, neke atu i te 90% he feldspar me te quartz, ko te feldspar te nuinga. He mā te nuinga o te wā he hina, he whero te kiko o te feldspar, ā, he mā te nuinga o te quartz, he hina te tae, he hina rānei, koinei te tae taketake o te karāneti. He kohuke mārō te feldspar me te quartz, ā, he uaua ki te neke ki te maripi maitai. Mō ngā ira pōuri o te karāneti, ko te nuinga he mika pango, kei reira ētahi atu kohuke. Ahakoa he ngawari te biotite, kāore i te ngoikore tōna kaha ki te ātete i te ahotea, ā, i te wa ano he iti te nui o te karāneti, he iti iho i te 10% te nuinga. Koinei te āhua o te rauemi e tino kaha ai te karāneti.

Ko tētahi atu take he pakari te karāneti, he piripono te here o ngā matūriki kohuke tetahi ki tetahi, ā, e piri ana tetahi ki tetahi. He iti iho i te 1% o te rōrahi katoa o te toka ngā pūwero. Mā tēnei ka taea e te karāneti te tu atu i ngā pēhanga kaha, ā, kāore e ngāwari te uru ki roto i te makuku.

He kōhatu ngā wāhanga karāneti, kāore he waikura, he ātete waikawa me te kawakore, he ātete pai ki te kakahu, ā, he roa te ora o te mahi, kāore he tiaki motuhake. Ko ngā wāhanga tika o te karāneti te nuinga o te wā e whakamahia ana i roto i ngā taputapu o te umanga mīhini. Nō reira, ka kiia rātou he wāhanga tika o te karāneti, he wāhanga karāneti rānei. He rite tonu ngā āhuatanga o ngā wāhanga tika o te karāneti ki ērā o ngā papa karāneti. He kupu whakataki ki te taputapu me te ine i ngā wāhanga tika o te karāneti: Ko te miihini tika me te hangarau miihini moroiti he huarahi whanaketanga nui o te umanga hanga mīhini, ā, kua waiho hei tohu nui hei ine i te taumata hangarau teitei. Ko te whanaketanga o te hangarau hou me te umanga parepare e kore e taea te wehe i te miihini tika me te hangarau miihini moroiti. Ka taea te nekeneke maeneene i ngā wāhanga karāneti i roto i te ine, me te kore e tū. Ko te ine i te mata mahi, ko ngā karawarawa whānui kāore e pā ki te tika o te ine. Me hoahoa me te whakaputa i ngā wāhanga karāneti kia rite ki ngā whakaritenga o te taha tono.

Mara tono:

E mōhio ana tātou katoa, he maha ake ngā mīhini me ngā taputapu e whiriwhiri ana i ngā wāhanga o te karāhe tino tika.

Ka whakamahia ngā wāhanga karāhe mō te nekehanga hihiri, ngā motuka raina, te cmm, te cnc, te mīhini taiaho...

Nau mai ki te whakapā mai mō ētahi atu kōrero.

He mea hanga ngā taputapu ine karāneti me ngā wāhanga miihini karāneti ki te karāneti pango Jinan kounga teitei. Nā te tino tika, te roa o te wā, te pumau me te ātete ki te waikura, kua nui haere te whakamahinga o ēnei taputapu i roto i te tirotiro hua o ngā ahumahi hou me ngā mara pūtaiao pēnei i te miihini ā-rangi me ngā rangahau pūtaiao.

Ngā Painga

----E rua te pakeke atu i te rino maka;

----Nā te huringa o te pāmahana ngā huringa iti o te rahinga;

----Kāore e pēhia, kia kore ai e whakararuraru i te mahi;

----Kāore he pūwero, he kokiri rānei nā te hanganga o te kōpura me te piri iti, e whakarite ana i te papatahi teitei mō te roa o te wā mahi, ā, kāore e kino ki ētahi atu wāhanga, ki ngā taputapu rānei;

----He mahi kore raruraru mō te whakamahi me ngā rauemi aukume;

----He roa te ora, kāore he waikura, he iti hoki ngā utu tiaki.

He mea hanga ngā pereti mata karāhe tino tika ki te paerewa teitei o te papatahi kia tika ai, ā, e whakamahia ana hei turanga mō te whakairi i ngā pūnaha ine hangarau, hiko me te whatu matatau.

Ko ētahi o ngā āhuatanga ahurei o te pereti mata karāhe:

Te ōritetanga o te mārō;

Ngā Tikanga Tika i raro i te kawenga;

Ārai wiri;

Ngāwari ki te Horoi;

Ātete ki te takai;

Iti te Pūngao;

Kore-whakakoi;

Kore-Aukume

Ngā Painga o te Pereti Mata Granite

First, the rock after a long period of natural aging, uniform structure, coefficient minimum, the internal stress completely disappear, not deformed, so the precision is high.

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Precision Granite Base Can Improve Machine Tool Performances

Requirements are constantly increasing in mechanical engineering in general and in machine tool construction in particular. Achieving maximum precision and performance values without increasing costs are constant challenges to being competitive. The machine tool bed is a decisive factor here. Therefore, more and more machine tool manufacturers are relying on granite. Due to its physical parameters, it offers clear advantages that cannot be achieved with steel or polymer concrete.

Granite is a so-called volcanic deep rock and has a very dense and homogeneous structure with an extremely low coefficient of expansion, low thermal conductivity and high vibration damping.

Below you will discover why the common opinion that granite is mainly only suitable as machine base for high-end coordinate measuring machines is long outdated and why this natural material as a machine tool base is a very advantageous alternative to steel or cast iron even for high-precision machine tools.

We can manufacture granite components for dynamic motion, granite components for linear motors, granite components for ndt, granite components for xray, granite components for cmm, granite components for cnc, granite precision for laser, granite components for aerospace, granite components for precision stages...

High Added Value Without Additional Costs
The increasing use of granite in mechanical engineering is not so much due to the massive increase in the price of steel. Rather, it is because the added value for the machine tool achieved with a machine bed made of granite is possible at very little or no extra cost. This is proven by cost comparisons of well-known machine tool manufacturers in Germany and Europe.

The considerable gain in thermodynamic stability, vibration damping and long-term precision made possible by granite cannot be achieved with a cast iron or steel bed, or only at relatively high cost. For example, thermal errors can account for up to 75% of the total error of a machine, with compensation often attempted for by software – with moderate success. Due to its low thermal conductivity, granite is the better foundation for long-term precision.

With a tolerance of 1 μm, granite easily meets the flatness requirements according to DIN 876 for the degree of accuracy 00. With a value of 6 on the hardness scale 1 to 10, it is extremely hard, and with its specific weight of 2.8g/cm³ it almost reaches the value of aluminium. This also results in additional advantages such as higher feed rates, higher axis accelerations and an extension of the tool life for cutting machine tools. Thus, the change from a cast bed to a granite machine bed moves the machine tool in question into the high-end class in terms of precision and performance – at no extra cost.

Granite’s Improved Ecological Footprint
In contrast to materials such as steel or cast iron, natural stone does not have to be produced with a great deal of energy and using additives. Only relatively small amounts of energy are required for quarrying and surface treatment. This results in a superior ecological footprint, which even at the end of a machine’s life surpasses that of steel as a material. The granite bed can be the basis for a new machine or be used for completely different purposes such as shredding for road construction.

Nor are there any shortages of resources for granite. It is a deep rock formed from magma within the earth’s crust. It has ‘matured’ for millions of years and is available in very large quantities as a natural resource on almost all continents, including all of Europe.

Conclusion: The numerous demonstrable advantages of granite compared to steel or cast iron justify the increasing willingness of mechanical engineers to use this natural material as a foundation for high-precision, high-performance machine tools. Detailed information about granite properties, which are advantageous for machine tools and mechanical engineering, can be found in this further article.

A repeat measurement is a measurement of local flatness areas. The Repeat Measurement specification states that a measurement taken anywhere on the surface of a plate will repeat within the stated tolerance. Controlling local area flatness tighter than overall flatness guarantees a gradual change in surface flatness profile thereby minimizing local errors.

Most manufacturers, including imported brands, adhere to the Federal Specification of overall flatness tolerances but many overlook the repeat measurements. Many of the low value or budget plates available in the market today will not guarantee repeat measurements. A manufacturer who does not guarantee repeat measurements is NOT producing plates that meet the requirements of ASME B89.3.7-2013 or Federal Specification GGG-P-463c, or DIN 876, GB, JJS...

Both are critical to ensure a precision surface for accurate measurements. Flatness specification alone is not sufficient to guarantee measurement accuracy. Take as an example, a 36 X 48 Inspection Grade A surface plate, which meets ONLY the flatness specification of .000300". If the piece being checked bridges several peaks, and the gage being used is in a low spot, the measurement error could be the full tolerance in one area, 000300"! Actually, it can be much higher if the gage is resting on the slope of an incline.

Errors of .000600"-.000800" are possible, depending upon the severity of the slope, and the arm length of the gage being used. If this plate had a Repeat Measurement specification of .000050"F.I.R. then the measurement error would be less than .000050" regardless of where the measurement is taken on the plate. Another problem, which usually arises when an untrained technician attempts to resurface a plate on-site, is the use of Repeat Measurements alone to certify a plate.

The instruments that are used to verify repeatability are NOT designed to check overall flatness. When set to zero on a perfectly curved surface, they will continue to read zero, whether that surface is perfectly flat or perfectly concave or convex 1/2"! They simply verify the uniformity of the surface, not the flatness. Only a plate that meets both the flatness specification AND the repeat measurement specification truly meets the requirements of ASME B89.3.7-2013  or Federal Specification GGG-P-463c.

Ask us about or flatness specification and repeat measurement promise by calling +86 19969991659 or emailing INFO@ZHHIMG.COM

Yes, but they can only be guaranteed for a specific vertical temperature gradient. The effects of thermal expansion on the plate could easily cause a change in accuracy greater than the tolerance if there is a change in the gradient. In some cases, if the tolerance is tight enough, the heat absorbed from overhead lighting can cause enough of a gradient change over several hours.

Granite has a coefficient of thermal expansion of approximately .0000035 inches per inch per 1°F. As an example: A 36" x 48" x 8" surface plate has an accuracy of .000075" (1/2 of Grade AA) at a gradient of 0°F, the top and bottom are the same temperature. If the top of the plate warms up to the point where it is 1°F warmer than the bottom, the accuracy would change to .000275" convex ! Therefore, ordering a plate with a tolerance tighter than Laboratory Grade AA should only be considered if there is adequate climate control.

A surface plate should be supported at 3 points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered. Only 3 points can rest solidly on anything but a precision surface.

The plate should be supported at these points during production, and it should be supported only at these three points while in use. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same 3 points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. All zhhimg steel stands have support beams designed to line up with the proper support points.

If the plate is properly supported, precise leveling is only necessary if your application calls for it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

Why Choose Granite for Machine Bases and Metrology Components?

The answer is 'yes' for almost every application. The advantages of granite include: No rust or corrosion, almost immune to warping, no compensating hump when nicked, longer wear life, smoother action, greater precision, virtually non-magnetic, low co-efficient of thermal expansion, and low maintenance cost.

Granite is a type of igneous rock quarried for its extreme strength, density, durability, and resistance to corrosion. But granite is also very versatile– it’s not just for squares and rectangles! In fact, Starrett Tru-Stone confidently works with granite components engineered in shapes, angles, and curves of all variations on a regular basis—with excellent outcomes.

Through our state of the art processing, cut surfaces can be exceptionally flat. These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components. Granite is:

machineable
precisely flat when cut and finished
rust resistant
durable
long lasting
Granite components are also easy to clean. When creating custom designs, be sure to choose granite for its superior benefits.

STANDARDS / HIGH WEAR APPLICATIONS
The granite utilized by ZhongHui for our standard surface plate products has high quartz content, which provides greater resistance to wear and damage. Our Superior Black and Crystal Pink colors have low water absorption rates, minimizing the possibility of your precision gages rusting while setting on the plates. The colors of granite offered by ZhongHui result in less glare, which means less eyestrain for individuals using the plates. We have chosen our granite types while considering thermal expansion in an effort to keep this aspect minimal.

CUSTOM APPLICATIONS
When your application calls for a plate with custom shapes, threaded inserts, slots or other machining, you’ll want to select a material like Black Diabase. This natural material offers superior stiffness, excellent vibration dampening, and improved machinability.

Yes, if they are not too badly worn. Our factory setting and equipment allow the optimum conditions for proper plate calibration and rework if necessary. Generally, if a plate is within .001" of the required tolerance, it can be resurfaced on-site. If a plate is worn to the point where it is more than .001" out of tolerance, or if it is badly pitted or nicked, then it will need to be sent to the factory for grinding prior to relapping.

Great care should be exercised in selecting an on-site calibration and resurfacing technician. We urge you to use caution in selecting your calibration service. Ask for accreditation and verify the equipment that the technician will use has a National Inspection Institution traceable calibration. It takes many years to learn how to properly lap precision granite.

ZhongHui provides quick turn-around on calibrations performed in our factory. Send your plates in for calibration if possible. Your quality and reputation depend on the accuracy of your measurement instruments including surface plates!

Our black surface plates have a significantly higher density and are up to three times as stiff. Therefore, a plate made of the black does not need to be as thick as a granite plate of the same size to have equal or greater resistance to deflection. Reduced thickness means less weight and lower shipping costs.

Beware of others who use lower quality black granite in the same thickness. As stated above, properties of granite, like wood or metal, vary by material and color, and is not an accurate predictor of stiffness, hardness, or wear resistance. In fact, many types of black granite and diabase are very soft and not suitable for surface plate applications.

No. The specialized equipment and training necessary to rework these items requires that they be returned to the factory for calibration and rework.

Yes. Ceramic and granite have similar characteristics, and the methods used to calibrate and lap granite can be used with ceramic items as well. Ceramics are more difficult to lap than granite resulting in a higher cost.

Yes, provided that the inserts are recessed below the surface. If steel inserts are flush with, or above the surface plane, they must be spot-faced down before the plate can be lapped. If required, we can provide that service.

Yes. Steel inserts with the desired thread (English or metric) can be epoxy bonded into the plate at the desired locations. ZhongHui uses CNC machines to provide the tightest insert locations within +/- 0.005”. For less critical inserts, our locational tolerance for threaded inserts is ±.060". Other options include steel T-Bars and dovetail slots machined directly into the granite.

Inserts that are properly bonded using high strength epoxy and good workmanship will withstand a great deal of torsional and shear force. In a recent test, using 3/8"-16 threaded inserts, an independent testing laboratory measured the force required to pull an epoxy-bonded insert from a surface plate. Ten plates were tested. Out of these ten, in nine cases, the granite fractured first. The average load at the point of failure was 10,020 lbs. for gray granite and 12,310 lbs. for black. In the single case where an insert pulled free of the plate, the load at the point of failure was 12,990 lbs.! If a work piece forms a bridge across the insert and extreme torque is applied, it is possible to generate enough force to fracture the granite. Partially for this reason, ZhongHui gives guidelines for the maximum safe torque that can be applied the epoxy bonded inserts: https://www.zhhimg.com/standard-thread-inserts-product/

Yes, but only at our factory. At our plant, we can restore almost any plate to 'like-new' condition, usually for less than half the cost of replacing it. Damaged edges can be cosmetically patched, deep grooves, nicks, and pits can be ground out, and the attached supports can be replaced. In addition, we can modify your plate to increase its versatility by adding solid or threaded steel inserts and cutting slots or clamping lips, per your specifications.

Why Choose Granite?
Granite is a type of igneous rock formed in the Earth millions of years ago. The composition of igneous rock contained many minerals such as quartz that is extremely hard and wear-resistant. In addition to hardness and wear resistance granite has approximately half the coefficient of expansion as cast iron. As its volumetric weight is approximately one third that of cast iron, granite is easier to manoeuvre.

For machine bases and metrology components, black granite is the colour most used. Black granite has a higher percentage of quartz than other colours and is, therefore, the hardest wearing.

Granite is cost-effective, and cut surfaces can be exceptionally flat. Not only can it be hand lapped to achieve extremes of accuracy, but re-conditioning can be performed without moving the plate or table off-site. It is entirely a hand lapping operation and generally costs much less than re-conditioning a cast iron alternative.

These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components such as the granite surface plate.

ZhongHui produces bespoke granite products that are created to support specific measurement requirements. These bespoke items vary from straight edges to tri squares. Due to the versatile nature of granite, the components can be produced to any size required; they are hard wearing and long-lasting.

Advantages of Granite Surface Plates
The importance of measuring on an even surface was established by British inventor Henry Maudsley in the 1800s. As a machine tool innovator, he determined that consistent production of parts required a solid surface for reliable measurements.

The industrial revolution created a demand for measuring surfaces, so engineering company Crown Windley created manufacturing standards. The standards for surface plates were first set by Crown in 1904 using metal. As the demand and cost for metal increased, alternative materials for the measuring surface were investigated.

In America, monument creator Wallace Herman established that black granite was an excellent surface plate material alternative to metal. As granite is non-magnetic and doesn’t rust, it soon became the preferred measuring surface.

A granite surface plate is an essential investment for laboratories and test facilities. A granite surface plate of 600 x 600 mm can be mounted on a support stand. The stands provide a working height of 34” (0.86m) with five adjustable points for levelling.

For reliable and consistent measurement results, a granite surface plate is crucial. As the surface is a smooth and stable plane, it enables instruments to be carefully manipulated.

The main advantages of granite surface plates are:

• Non-reflective
• Resistant to chemicals and corrosion
• Low coefficient of expansion compared with cart iron so less affected by temperature change
• Naturally rigid and hard-wearing
• The plane of the surface is unaffected if scratched
• Will not rust
• Non-magnetic
• Easy to clean and maintain
• Calibration and resurfacing can be done onsite
• Suitable for drilling for threaded support inserts
• High vibration damping

For many shops, inspection rooms and laboratories, precision granite surface plates are relied on as the basis for accurate measurement. Because every linear measurement depends on an accurate reference surface from which final dimensions are taken, surface plates provide the best reference plane for work inspection and layout prior to machining. They also are ideal bases for making height measurements and gaging surfaces. Further, a high degree of flatness, stability, overall quality and workmanship make them a good choice for mounting sophisticated mechanical, electronic and optical gaging systems. For any of these measurement processes, it is imperative to keep surface plates calibrated.

Repeat Measurements and Flatness
Both flatness and repeat measurements are critical to ensure a precision surface. Flatness can be considered as all points on the surface being contained within two parallel planes, the base plane and the roof plane. The measurement of distance between the planes is the overall flatness of the surface. This flatness measurement commonly carries a tolerance and may include a grade designation.

The flatness tolerances for three standard grades are defined in the federal specification as determined by the following formula:
Laboratory Grade AA = (40 + diagonal² / 25) x 0.000001 inch (unilateral)
Inspection Grade A = Laboratory Grade AA x 2
Tool Room Grade B = Laboratory Grade AA x 4

In addition to flatness, repeatability must be ensured. A repeat measurement is a measurement of local flatness areas. It is a measurement taken anywhere on the surface of a plate that will repeat within the stated tolerance. Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.

To ensure a surface plate meets both the flatness and repeat measurement specifications, manufacturers of granite surface plates should use Federal Specification GGG-P-463c as a basis for their specifications. This standard addresses repeat measurement accuracy, material properties of surface plate granites, surface finish, support point location, stiffness, acceptable methods of inspection and installation of threaded inserts.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

Checking Plate Accuracy
By following a few simple guidelines, an investment in a granite surface plate should last for many years. Depending on plate usage, shop environment and required accuracy, frequency of checking the surface plate accuracy varies. A general rule of thumb is for a new plate to receive a full recalibration within one year of purchase. If the plate is used frequently, it is advisable to shorten this interval to six months.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

An effective inspection program should include regular checks with an autocollimator, providing actual calibration of overall flatness traceable to National Institute of Standards and Technology (NIST). Comprehensive calibration by the manufacturer or an independent company is necessary from time to time.

Variations Between Calibrations
In some cases, there are variations between surface plate calibrations. Sometimes factors such as surface change resulting from wear, incorrect use of inspection equipment or use of noncalibrated equipment can account for these variations. The two most common factors, however, are temperature and support.

One of the most important variables is temperature. For instance, the surface might have been washed with a hot or cold solution prior to calibration and not allowed sufficient time to normalize. Other causes of temperature change include drafts of cold or hot air, direct sunlight, overhead lighting or other sources of radiant heat on the surface of the plate.

There also can be variations in the vertical temperature gradient between winter and summer. In some cases, the plate is not allowed sufficient time to normalize after shipment. It is a good idea to record the vertical gradient temperature at the time the calibration is performed.

Another common cause for calibration variation is a plate that is improperly supported. A surface plate should be supported at three points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered.

Only three points can rest solidly on anything but a precision surface. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same three points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. Consider using steel stands with support beams designed to line up with the proper support points. Stands for this purpose are generally available from the surface plate manufacturer.

If the plate is properly supported, precise leveling is only necessary if an application specifies it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

It is important to keep the plate clean. Airborne abrasive dust is usually the greatest source of wear and tear on a plate, as it tends to embed in workpieces and the contact surfaces of gages. Cover plates to protect them from dust and damage. Wear life can be extended by covering the plate when not in use.

Extend Plate Life
Following a few guidelines will reduce wear on a granite surface plate and ultimately, extend its life.

First, it is important to keep the plate clean. Airborne abrasive dust is usually the greatest source of wear and tear on a plate, as it tends to embed in workpieces and the contact surfaces of gages.

It also is important to cover plates to protect it from dust and damage. Wear life can be extended by covering the plate when not in use.

Rotate the plate periodically so that a single area does not receive excessive use. Also, it is recommended to replace steel contact pads on gaging with carbide pads.

Avoid setting food or soft drinks on the plate. Many soft drinks contain either carbonic or phosphoric acid, which can dissolve the softer minerals and leave small pits in the surface.

Where to Relap
When a granite surface plate needs re-surfacing, consider whether to have this service performed on-site or at the calibration facility. It is always preferable to have the plate relapped at the factory or a dedicated facility. If, however, the plate is not too badly worn, generally within 0.001 inch of the required tolerance, it can be resurfaced on-site. If a plate is worn to the point where it is more than 0.001 inch out of tolerance, or if it is badly pitted or nicked, then it should be sent to the factory for grinding prior to relapping.

A calibration facility has the equipment and factory setting providing the optimum conditions for proper plate calibration and rework if necessary.

Great care should be exercised in selecting an on-site calibration and resurfacing technician. Ask for accreditation and verify the equipment that the technician will use has a NIST-traceable calibration. Experience also is an important factor, as it takes many years to learn how to correctly lap precision granite.

Critical measurements start with a precision granite surface plate as a baseline. By ensuring a reliable reference by using a properly calibrated surface plate, manufacturers have one of the essential tools for reliable measurements and better quality parts.

Checklist for Calibration Variations

1. The surface was washed with a hot or cold solution prior to calibration and was not allowed sufficient time to normalize.
2. The plate is improperly supported.
3. Temperature change.
4. Drafts.
5. Direct sunlight or other radiant heat on the surface of the plate. Be sure that overhead lighting is not heating the surface.
6. Variations in the vertical temperature gradient between winter and summer. If at all possible, know the vertical gradient temperature at the time the calibration is performed.
7. Plate not allowed sufficient time to normalize after shipment.
8. Improper use of inspection equipment or use of noncalibrated equipment.
9. Surface change resulting from wear.

Tech Tips
Because every linear measurement depends on an accurate reference surface from which final dimensions are taken, surface plates provide the best reference plane for work inspection and layout prior to machining.

Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.