Tolerances
Gbogbo ọrọ náà
Nothing is ever made to size. Cut a hundred pieces of timber to 300 millimetres and you will have a hundred pieces measuring between about 299 and 301, and if you measure them precisely enough, no two will be identical. That is not a failure of skill, it is how making works, and a designer who has not accepted it will produce drawings that cannot be manufactured and will spend their career blaming the workshop.
A tolerance is the amount by which a dimension is allowed to differ from the size on the drawing, and it is the designer's statement of how much variation the product can survive. This lesson covers working accurately using tolerances, how a range of materials are cut, shaped and formed to designated tolerances, and why tolerances are applied during making activities at all. You will calculate limits, work with percentage tolerances, see why errors accumulate and how a datum stops them, and decide how tight a tolerance ought to be, which is the judgement that separates a designer from somebody who writes small numbers. This is designing and making principles content, examined in Section C of Paper 1.
Ebumnobi
- Work accurately using tolerances. How a range of materials are cut, shaped and formed to designated tolerances. Why tolerances are applied during making activities.
Maapụ uche
E seela isiokwu a ka ị hụ otu echiche si ejikọta.
Mepee maapụ uche na ngwa
Akwụkwọ Ọmụmụ
Ndetu Nkuzi Zuru Ezu di na Ngwa Green Bridge
Nweta ngwa Green Bridge CBT na ekwenti gi ma o bu kompiuta maka ulo akwukwo IGCSE zuru oke: akwukwo ule ndi gara aga, usoro nyocha, eserese uche, kaadi omumu na nkuzi olu.
Nnyocha Ọmụmụ
Ekele diri gi maka imecha ihe karịrị na Tolerances. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.
Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.
Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.
- A dimension is given as 30 plus 0.3 minus 0.2 millimetres. What is the tolerance? A. 0.1 millimetres B. 0.2 millimetres C. 0.3 millimetres D. 0.5 millimetres Answer: D
- A length of 400 millimetres has a tolerance of plus or minus 1.5 per cent. What are the limits? A. 398.5 and 401.5 B. 394 and 406 C. 385 and 415 D. 340 and 460 Answer: B
- Four spacers each 5.0 plus or minus 0.1 millimetres thick are stacked. What is the maximum possible height of the stack? A. 20.1 millimetres B. 20.2 millimetres C. 20.4 millimetres D. 24.0 millimetres Answer: C
- Dimensioning every feature from one chosen face rather than from the previous feature is done in order to A. save drawing time. B. prevent errors from accumulating. C. reduce the material cost. D. avoid the need for a tolerance. Answer: B
- Why should a designer avoid specifying a tolerance tighter than the process can achieve? A. It makes the drawing harder to read B. It produces rejects and raises the cost without improving the product C. It is not allowed by the specification D. It removes the need for a datum Answer: B
Rue ajuju ndi a n'ime ngwa ahu
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Meecha Ajụjụ Ule Ọmarịcha
Ị chọrọ ime ajụjụ ule ọmarịcha gbasara Tolerances? Budata ngwa Green Bridge CBT iji nweta ajụjụ ule ọmarịcha na nyocha zuru ezu gbasara isiokwu a.
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