The Problem:

This customer approached us at a trade show looking for help to solve a severe abrasion problem coupled with product contamination. The process is proprietary and details are confidential.

This is a Powder Injection Molding process and, as is common to this process, parts are sintered after molding to achieve final size and part density. Clarity of the finished part was extremely important and any contaminants in the process usually showed up as a darkening of the sintered part.

These are small parts being processed on small 30 ton machines. Past wear protection consisted of a surface hardening treatment to infuse an elemental material into the screw surface resulting in a hard layer. High temperatures were required to achieve this layer and post heat treat straightening was difficult. The result was a screw and barrel with a large initial clearance of about .009”, which accelerated wear and shortened component life. Hard surfaced screws lasted about 3 months and 300,000 shots until product contamination lead to too much scrap and the screw was replaced.

As this hard layer wears, the softer substrate is exposed, which accelerates wear. More importantly, wear increases the amount of contaminants in the finished product causing a loss of clarity. Scrap goes up.

The Solution:

A screw was encapsulated with .005” of our XC9000 Millennium carbide for fine particle abrasion. This coated screw was installed in a surface hardened barrel with a combined clearance of .002” between screw and barrel. In three months of steady operation this system produced 500,000 shots of high clarity useable parts. The screw was measured and had total OD wear of only .001”.

Benefits:

The coated feed screw will last significantly longer than previous screws and produce high quality product. This combination provides the customer a competitive advantage and has allowed them to increase their global market share for this product line.