GlossaryKind of term: Manufacturing termAssembly
What is an assembly?
An assembly is an item made up of several parts, made or bought in, joined into one unit by fitting, welding, pressing or another connection.
Besides made and bought-in parts, the items can include subassemblies, and the joint can also be bonded. For example, a module with a milled frame, two turned shafts, four bearings and a motor. The customer usually supplies an assembly drawing with item numbers and a bill of materials, plus a drawing and model for each made part. A weldment is often treated as an assembly, even though it cannot be taken apart; exactly how follows from the structure of the customer's bill.
How does an assembly work in practice?
The cost of an assembly is a sum: each made part with its own estimate, each bought-in part at its purchase price, with any mark-up for purchasing and handling, times the quantity per assembly, and your own work such as fitting, welding, adjusting or testing as a separate item. Errors tend to come from the counting: an item counted twice, as a line in the bill and again in the fitting work, or work of your own that sits in no line at all. Technically an assembly depends on the tolerances between the parts: fits and tolerance chains decide whether parts go together without rework, and some features are only machined once assembled. The delivery date also depends on the item with the longest lead time.
What is an assembly often confused with?
An assembly is not a part: a part is a single item, an assembly consists of several items plus work of its own. And the bill of materials only lists what goes into it; the assembly is the thing itself.
How do you see an assembly in Blake?
In Blake an assembly is one whole with its items beneath it: made parts with their own estimate, bought-in parts as lines of their own with their purchase price, and the assembly's own work as its own line. Together they roll up to one total; a bought-in part without a price stays open in it and does not count as zero. More on estimating.
Frequently asked questions
How do I estimate an assembly with bought-in parts?
Each made part gets its own estimate, each bought-in part a line with your supplier's price and the quantity per assembly, and your own work an item of its own. The total is the sum; an item that occurs several times counts that many times.
Is the customer's CAD assembly the same as the bill of materials?
No. The CAD assembly shows what was modelled; the bill says what you buy, make and fit, including items with no model such as adhesive, threadlocker or cables. Set them side by side before you calculate.
Should assembly time be estimated separately?
Yes, as an item of its own. Fitting, adjusting, testing and packing depend on the number of joints and fits, access and the requirements on the finished product. A fixed mark-up on the parts can reflect that poorly.