Manufacturing Processes & Techniques Flashcards

In injection molding, 'sink marks' on a plastic part are most commonly caused by:

Answer: Insufficient cooling time leading to localized shrinkage at thick sections

Sink marks form when thick sections cool and shrink inward before the outer skin solidifies, creating visible depressions on the part surface.

Which honing process characteristic distinguishes it from grinding?

Answer: Honing uses abrasive stones with reciprocating and rotating motion at low speed to improve bore geometry

Honing uses bonded abrasive stones that simultaneously rotate and reciprocate at relatively low speeds, primarily improving bore geometry, surface finish, and size accuracy.

The Taylor tool life equation (VT^n = C) describes the relationship between cutting speed and tool life. What does a higher value of the exponent 'n' indicate?

Answer: The tool material is less sensitive to cutting speed — tool life changes less with speed variation

A higher 'n' value (closer to 1) means tool life is less sensitive to changes in cutting speed, indicating a more thermally stable tool-workpiece combination.

In sheet metal bending, 'springback' refers to:

Answer: The elastic recovery of the bent sheet that reduces the final bend angle after the load is removed

Springback is the elastic recovery that occurs when the bending force is released, causing the part to partially return toward its original shape and reducing the achieved bend angle.

Which non-destructive testing (NDT) method is most effective for detecting subsurface cracks in non-ferromagnetic conductive materials like aluminum?

Answer: Eddy current testing

Eddy current testing uses electromagnetic induction to detect subsurface discontinuities in conductive materials, including non-ferrous metals like aluminum.

In forging operations, 'flash' is the thin fin of excess material that forms at the parting line. Its primary function during closed-die forging is to:

Answer: Create back-pressure that forces metal to fill all die cavities completely

Flash creates resistance in the flash gutter, generating back-pressure that forces the workpiece material to flow into and completely fill all details of the die cavity.

What is the primary difference between plasma arc cutting and oxyfuel cutting?

Answer: Plasma arc cutting uses ionized gas at high temperatures and can cut any electrically conductive material, including stainless steel and aluminum

Plasma arc cutting melts and expels material using a high-temperature ionized gas jet, making it effective on any conductive metal, while oxyfuel relies on oxidation and is limited to carbon steels.