Making One, Making Thousands
Making many copies can spread upfront tooling costs across a larger run. Compare total costs and flexibility before choosing a method. Tolerances, jigs and templates help parts meet a repeatable specification.
What a learner can do afterwards
- Explain how production volume affects tooling cost per item and compare total costs before choosing a mould
- Say what a size tolerance permits and why parts that fit together need compatible limits
- Distinguish a drilling jig that holds and guides from a template that provides a repeated outline
- Compare one-off, batch and mass production on cost per item and flexibility
1 · Read
You have seen how machine limits affect a CAD design. The number of copies also affects the making method. A mould may have a setup charge paid before production starts. Average cost per item includes that charge divided by the number made. One item carries it all; more items share it. Materials and labour still cost money.
Suppose a badge mould costs £200 and making each badge then costs £1. Hand making costs £6 per badge with no setup charge. Total cost = setup cost + (cost per badge × number made). For 20 badges, moulding costs £220 and hand making £120. For 200, the totals are £400 and £1,200. These are invented quotes for equal quality. Compare actual quotes before choosing.
A size tolerance gives the permitted variation in a dimension. If a spacer may be 29 mm to 31 mm long, including both limits, a 30 mm spacer meets that tolerance. Parts that fit together need compatible limits. For example, a pin must fit its hole across the permitted sizes. A tolerance allows variation; it does not demand identical copies.
A drilling jig holds a part and guides the drill so holes repeat in the required position. A template provides a pattern for marking or cutting a repeated outline. It need not hold the part. These tools help reduce variation, but the finished parts still need checking against their specification.
One-off production makes one item, often using adjustable tools. Batch production makes a set, then may change the setup for another set. Mass production makes many copies of a standard design. Dedicated tooling can lower cost per item at high volume, but design changes may be costly. Compare unit cost with flexibility: how easily and cheaply can the method accommodate changes?
Compare setup and per-item costs. Match the method to the quantity, likely design changes and required specification.
Lesson, questions and flashcards written for this dataset about production costs, compatible tolerances, jigs and templates. Cost examples use invented quotes.
2 · Watch
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