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MatrixLogo horizontal white

Injection Molding and Moldmaking
with Surgical Precision

Injection Molding and Moldmaking
with Surgical Precision

Call us: (630) 595-6144

Call us: (630) 595-6144

By Tom Ziegenhorn

September 28, 2012

Objet30 Desktop 3D Printer

Recently, Matrix purchased an Objet30 3D printer for our mold design & engineering department. Adding this in-house capability is very much in keeping with the way our company conducts its business: we try do most everything in-house, including designing and building our own molds.  So having a 3D printer allows us to offer in-house rapid prototyping services to our customers, 70% of whom are medical device OEM’s who rely on us to help bring their cutting-edge products from concept to reality.  Now we can produce 3D printed prototypes from a customer's data model within hours versus the typical three- to five-day wait time for an outside service. 

Providing physical part samples you can hold in your hand is a value-added service and especially helpful during the R&D phase of a new project, particularly when very small, complex parts, overmolded components, assemblies, or secondary operations are involved.  It's really beneficial for both our customer and us.  Everyone gets a much clearer view of the project, and we can experiment with ideas of how to make things better, faster and more economically.

Additionally, we are using this technology to produce fixtures for inspections and secondary operations, instead of conventionally machining them. 

In a recent blog posting we discussed the consequences of molding with wet engineering and commodity resins. The best way of dealing with these consequences is to avoid them entirely. In the posting we discussed our procedures and test equipment for assuring that the dryness of the resin is in the correct range. The most important aspect of resin drying is, of course, the dryer and the maintenance of the dryer.

At Matrix Plastic Products, we have a dedicated dryer for each molding machine that runs hygroscopic engineering resins. The dryers are of two types:

1. Desiccant hot-air dryers
2. Compressed air dryers

Key to dryer effectiveness is maintenance. If the dryer goes down, the molding machine might as well be down. At Matrix, we take a multifaceted approach to dryer maintenance.

Visual Inspection: Dryers are visually inspected daily for hose condition, clamps, and kinks. Controls are scanned for dew point and temperatures in the proper range. Air flow cones are inspected as are the air flow filters.

Monthly detailed inspection: This includes the moving parts, testing desiccant condition, and confirming dew point meter readings on the dryer with a hand held dew point meter.

All monthly inspections and maintenance are documented on a preventive maintenance spreadsheet, developed here at Matrix Tooling/Matrix Plastic Products. This sheet covers PM for most common injection molding room equipment and is available for free at: http://www.plasticstoday.com on the maintenance forum and also on Bill Tobin’s WJT Associates website: http://wjtassociates.com/site/.

Since the sheet was developed here at Matrix, it will soon be available on our main website, again, for free. The PM sheet has been used all over the world and is a great tool for any molder to have in his or her kit. So avoid the consequences of molding with wet resin and maintain those dryers!
Written by:

Brent Borgerson
Senior Process Engineer (Older Molder)

Drying engineering resins is crucial to obtaining desirable end products with these high–performance and often expensive resins. Thermoplastic resins are being called on to be as strong as metal and to survive in harsh environments. To achieve these end properties, a resin must be processed correctly, and one area of proper processing is to ensure that the resin is molded at or under the manufacturer’s specified maximum moisture content (%).

At Matrix Plastics Products, we are very careful (almost to the point of being neurotic) about our resin drying and dryness assurance procedures. We take a multi-pronged approach to these issues including some of the techniques and procedures as follows:

  • •  Drying Time: We follow the manufacturers’ recommendations as a minimum for drying time before beginning molding as well as residence time in the dryer. These steps are carefully documented for accountability.
  • •  Drying Temperature: Again, resin makers’ guidelines are strictly followed.
  • •  Dew Point Monitoring of the Dryer: Our dryers feature dew point monitors and alarms which are consistently observed. The dew point on a dryer is the best indication of the proper function of the dryer, which allows us to foresee many impending problems.
  • •  Moisture Analyzer: Our Quality Inspection lab features an OMNIMARK Mark IV moisture analyzer which can be used to test and verify results. This is the last line of defense and is used whenever there is any doubt about the dryness of a resin. In the case of sensitive jobs, moisture analyzing test are routinely used and documented.

A part molded with wet resin (moisture content above the manufacturer’s suggested max percentage) may not be a cosmetically unappealing part, but it is almost always a structurally weak part. Hydrolysis – the result of heating moist resin – produces an action in the resin that is essentially akin to thermal degradation. The molecular structure and integrity are affected, and a weak and/or brittle part is the result. Some of these problems are not always readily detectable, especially during the early life of the product, but premature and unexpected failures can result from molding with “less-than-dry” resin. We try our best to avoid this situation.

Written By:

Brent Borgerson
Senior Process Engineer (Older Molder)

Pat Collins
Molding Operations Manager

 

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