Plastics10 min read
Mixed-material assemblies: thermal expansion and corrosion
Why a joint between aluminium, steel and copper moves and corrodes, and the design details that keep it tight through temperature cycles and a wet service life.
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Topic hub
Plastics and assemblies
Electrical housings carry three jobs at once: structure, insulation and assembly. These guides cover wall sections, ribs, draft, material choice and the tolerances that keep a moulded part fitting.
Guides in this topic, page 3
Plastics8 min read
Mould flow analysis: what it catches
A fill, pack, cool and warp study can find a short shot, a hot spot or a bowed cover before the steel is cut. It can also be run on the wrong inputs and answer a question nobody asked.
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Plastics9 min read
Tooling for injection moulding: cavity, steel and cost
How cavity count, steel grade, runner type and side actions move a mould quote, and how to compare tooling on total cost rather than price alone.
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Plastics10 min read
Assembly cost model: labour, fixtures, test and yield
A line by line way to build an assembly cost, check a supplier quote and see which input is really moving the unit price.
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Plastics9 min read
Assembly testing: pull, torque and function
A test plan for mechanical assemblies: what each test proves, how to set the sample and the acceptance, and how to keep the fixture from inventing failures.
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Plastics8 min read
Bridge tooling vs production tooling
An aluminium or soft steel tool can put parts in customers' hands months before a hardened tool is ready. Here is what it can hold, what it cannot, and how to plan the handover.
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Plastics9 min read
Overmoulding: grips, seals and strain relief
Material pairs, bond lines and geometry for soft-touch overmoulds that stay attached, seal reliably and protect a cable at the entry point.
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Plastics9 min read
Undercuts and side actions: cost impact
Why an undercut blocks ejection, the four ways to mould one, and how a side action changes tool cost, cycle time, maintenance and the tolerance you can hold.
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Plastics10 min read
Assembly tolerance stack-up: worst case and statistical methods
How to add up the tolerances in a multi part assembly, when the worst case answer is the honest one, and how to read the result back onto the drawing.
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Plastics9 min read
Insert moulding: metal inserts in plastic housings
How to design a moulded-in insert so it holds torque, survives thermal cycling and does not crack the boss around it.
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Plastics9 min read
Ribs, bosses and gussets: design rules for moulded parts
How to add stiffness and screw fixings to a moulded part without sink marks, short shots or a boss that cracks on the assembly line.
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Plastics9 min read
Sub-assembly vs full assembly sourcing: control, cost and logistics
Where to draw the boundary between what you build and what a supplier builds, and how that line changes cost, risk and the speed at which you can change the product.
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