Know-How

Extrusion Know How 25 Sep 2017

Extrusion: The Role of Polymer Density in Screw Design

Density affects the mass flow rate, and energy transfer is based on mass, not volume. As a result, polymer density enters into practically every calculation in a screw design.

best practices 25 Sep 2017

Injection Molding: DOEs Done Right

Doing DOEs for the sake of doing them wastes time and money. But they can provide vital information to determine which process variable is determining a critical part characteristic.

best practices 25 Sep 2017

Cycle Time: Science vs. Rules of Thumb—Part 4

While laboratory tests are helpful in determining how polymers behave, you must remember the fundamental differences between laboratory measurements and the real world of plastic processing. Let’s examine semi-crystalline polymers here.

Extrusion Know How 31 Aug 2017

Extrusion: The Facts About Barrel-Temperature Override

Cooling the barrel more may extract heat from the barrel, but not necessarily from the process. Here’s why.

Injection Know How 31 Aug 2017

Injection Molding: Put Out the Production Fire Once and for All

A deliberate approach to failure assessment, root-cause analysis, solution development, and continued monitoring is the only way to get off the treadmill of chasing the latest production problem.

Materials Know How 30 Aug 2017

Materials—Cycle Time: Science vs. Rules of Thumb—Part 3

To properly calculate cycle time, you need to understand how the modulus of a polymer increases as it cools in the mold.

best practices 25 Jul 2017

Tooling: Critical Design Considerations for Sprue Bushings

Among them are good cooling, proper orientation, solid retention, structural integrity, generous radii, and an appropriately polished bore.

Extrusion Know How 25 Jul 2017

Extrusion: The Importance of Proper Barrel Supports

Supports that allow the barrel to expand and contract easily will prevent alignment issues. Examine them periodically for proper operation, particularly if you’re experiencing excessive wear.

scientific molding 25 Jul 2017

Injection Molding: Time for Another Look at Non-Return Valves

First and foremost, they must seal properly, and check valves with stepped angles or radiused seats perform the best.

Materials Know How 25 Jul 2017

Materials: Cycle Time: Science vs. Rules of Thumb—Part 2

Understanding cooling—how a given material develops modulus as it solidifies—requires access to data that provides some insight into the relationship between modulus and temperature. Dynamic mechanical analysis is a helpful tool.