Seals and Bushings

Material, process & control: You need all three to make things better

Effective Injection Molding is a lot more than simply injecting material into a mold. A complete-process vision for injection molding can give you a manufacturing edge that reduces costs, improves performance, enables tight tolerances and delivers consistently reproduceable quality. By considering material properties, rethinking production processes and tightly controlling conditions like temperature and flow, Hi Tech is creating parts and assemblies in ways they’ve never been created before and helping our customers deliver better products for less. Here are some example.

PEEK Seal Revolution: From $450 per Ring to < $50

Hi-Tech began dealing with Glass and PTFE filled PEEK seals for certain Aerospace applications in the mid 1990s. We followed the standard industry process by purchasing seals in five different sizes, from 3” to 9”. The seals are approximately 1/8” wide by .100 thick. Since they were machined from rod stock, more than 90% of the material was thrown away – a huge waste of expensive material.

Hi-Tech set out to slash the seal cost by moving the process from machining to molding and eliminating the material waste. The primary technical challenge moving from a machined seal to a molded seal was managing a tight tolerance gap that must be present in the ring. Hi-Tech used a combination of very tight temperature control and go/no go gauges to monitor the gap and manufacture to spec.

Hi-Tech’s injection molded Glass/PTFE filled PEEK seal rings went into production in 2014 and lowered the cost per ring from around $450 to less than $50 – a reduction of more than 80%.

PEEK Adapter & Back-up Rings: Manufacturing for O&G on the Wings of “Kentucky Windage”

Hi-Tech began producing adapter rings and back up rings that are part of larger Oil & Gas Industry ring stacks in 2017. We reduced cost, improved performance and increased lifespan by using Glass-filled PEEK to replace brass.

This was a very challenging manufacturing exercise because PEEK doesn’t necessarily want to uniformly flow into the shape you choose –especially based on a ring’s circularity requirements and the fact that PEEK is semi-crystalline. Add the fact that PEEK shrinks differently in flow versus cross flow directions, and it’s easy to understand why other manufacturers didn’t take on this challenge.

Hi-Tech invested the time and resources to fine tune a process that adjusts the injection mold tool so that the steel is not exactly like the final component geometry. The steel tool is made as an oval, but the molded part shrinks and cools to a circle. This is something Hi-Tech likes to call “Kentucky Windage,” after the process target shooters use to account for the effect of the wind on blustery ranges. We design the tool for the part’s final, cooled outcome.

This application went beyond ring molding. We helped our customer build more robust prints to reflect all their end-customer’s requirements and create a more complete solution. We went through several iterations of tooling to dial in tight tolerances and get it perfect. Lastly, Hi-Tech installed Go/No Go fixtures at each operation to ensure that parts are meeting print at all points, improving quality and reducing rejections.

Delrin Bushings: Innovative Molding or Precise Machining to Support Start Up and Production

Hi-Tech has been molding Delrin Bushings since the early 1990s. We began by machining rod and sheet stock on a lathe, leveraging our extensive, proven machining acumen. As our success led to increased demand, we decided to build a molding solution and mold bushings rather than machine them. In addition to keeping up with demand, we saw an opportunity to cut costs without compromising quality.

Getting started was an engineering and manufacturing exercise in give and take. We saw the solution as producing two different part geometries from the same tool with an insert change. After significant tool iterations due to unusual shrinkage caused a thick nominal wall, we hit on the perfect solution and could speed production of bushings exactly to spec tolerance.

As an added bonus, we reduced the cost from just under $25 for a machined part to just under $5 for a molded part. As owners of this proprietary methodology, Hi-Tech can support additional customers with custom bushing applications using this tooling. When we need to produce low volumes, we machine parts from rod stock. When volumes increase, we can move the bushings to injection molding, increasing production and reducing cost. It’s a classic win-win outcome.