C&H Blog

One of the first things we’ll consider in quoting the mold is the right class mold for your project. We can determine the best mold class based on the tolerances allowed on your prints, the approximate number of cycles your project requires and the budget you have to work with.

To help you with this, we’ve listed a few of the classes of molds with the estimated number of cycles the mold can produce along with a brief description of the mold.

Please note, even though each class has its own unique mold requirements, there are a few things that you will want to have on all molds, regardless of the class.

Some of these things are:

• Mold designs to be available for review and approval prior to start of construction.
• Complete set of mold drawings to be supplied with all finished molds.
• All molds and inserts (with the exception of prototype) to have adequate channels for
  temperature control.
• Mark all inserts with the type of steel and Rockwell Hardness.
• Vents at the parting line.
• In multi-cavity molds and/or inserts, all identical cavities are to be individually identified.

Mold Classifications

Class 101
Cycles: One million or more
Description: Built for extremely high production.  This is a top of the line mold made with only the highest quality materials.

Class 102
Cycles: Not to exceed one million
Description: Medium to high production mold. Good for abrasive materials and/or parts requiring close tolerances. This is a high quality mold.

Class 103
Cycles: Under 500,000
Description: Medium Production Mold.  This is a very popular mold for low to medium production needs. This is the most common mold type.

Class 104
Cycles: Under 100,000
Description: Low Production Mold. Used for limited production preferably with non-abrasive materials.

Class 105
Cycles: Not to exceed 500
Description: Prototype only. This mold will be constructed in the least expensive manner possible to produce a very limited quantity of prototype parts. It may be constructed from cast metal, epoxy or any other material offering sufficient strength to produce minimum prototype pieces.

Class 401 to 404
Description: These molds have similar requirements to the ones listed above, but are built with stronger materials to be sure they withstand running in injection molding presses rated above 400 tons.

Please click here for our complete guide describing all of the above mold class specifications and more…

Until next time,
Rollin

PS References for this post are based on the standards set in: Customs and Practices of the Moldmaking Industry; Classifications of Injection Molds for Thermoplastic Materials by the Moldmakers Division of The Society of the Plastics Industry, Inc.

You might think that you’re better off being specific as to the grade material for your part. The thing is, we’ve actually found that specifying a grade material in your blueprint can cost you time and money.

This is because the raw material industry is in a constant state of flux. Materials companies are buying, selling, and merging. Product lines change…or are eliminated! That’s why you only want to cite specific grades if absolutely necessary.

We do understand that there are times when customers must have a specific grade material on their blueprints (ie. for UL approval or for Medical parts). It’s no problem but please remember that if you do have a long list of product validation requirements to prove out new materials, you need to be sure to plan extra time for it.  If possible, try to specify multiple grades from different material sources. This could give you the time to come up with alternatives when needed.

The better way is to specify a generic material grade along with the actual requirements of the finished part that you consider important. Things like heat requirements, flammability ratings, UL and/or FDA requirements, chemical resistance etc. help us find the right material to make the best performing part possible.

Specifying generic grades and the part’s important requirements allows us greater flexibility in choosing the material that meets the demands of your part’s performance at the lowest cost.

As always, if you’re unsure or have questions, call us and we’ll talk about the materials that will make you the best part at the lowest cost.

Until next time,
Bill Clark

Step two after part design in the preproduction phase of your plastic part is the making of the prototype. This is where your creativity meets realty! Our rapid prototyping can produce an ABS plastic prototype for you in just days.

We use the Stratasys Dimension 3D Printer for our prototypes and we were pleased to learn that Fast Company magazine recently named Stratasys to its Transportation Top 10 list. Others honored include Boeing, GE, Daimler, and Nissan.

The recognition was to those that Fast Company regards as innovative with a product or business model that will have a major impact in transportation or the manufacture of transportation products.

It named Stratasys to the list for its work with KorEcologic, the company producing the Urbee hybrid. It’s a car that can run on the energy produced from a solar panel mounted on a garage and can get 200 mpg on gasoline or ethanol.

What caught our eye is that Stratasys was singled out because the production of the car’s components was with 3D Printing/3D Production. That’s the same way we make your rapid prototype.

It’s called 3D Printing and Fast Times liked the way it avoids the heavy tooling required for traditional production methods. We agree that it cuts waste, makes the process greener, and significantly reduces development time and associated costs.

Fast Company also wrote about all of this last October when Stratasys and KorEcologic announced they had teamed up. They called it the “…the First 3-D Printed Car.”

Here at C& H Plastics, we have a special offer with our 3D Printing…A FREE PROTOTYPE! We’ll refund the cost of one prototype model against your paid injection mold order (size limitations apply). So call us and we’ll discuss how rapid prototyping can save you time and lower your costs.

And here’s to Stratasys and KorEcologic…we wish them luck in the production of their incredible “green” car! May it some day advance from prototype to mass production.

Until next time,
Rollin

You’ll save time and money with plastic parts designed to be cost efficient and as easily moldable as possible. And remember, after you start building the mold or worse, once your parts are in the production phase, problems are much more expensive to fix.

Here are 5 tips to keep in mind for better plastic part design:

1) Think about adding draft angles to make sure your parts can be easily removed from the mold. Parts with longer or deeper side wall surface areas may need larger draft angles. Textured surfaces will also require larger draft angles because the parts are more likely to stick.

2) Don’t forget that even with draft added, you need to have some way to get the parts out of the mold.  To help keep the cost down on your mold, try to leave areas for ejector pins whenever possible. Some designs may require ejector blades or a stripper plate, but remember that these will add additional cost. Try to include the desired pin locations clearly in your drawings and keep in mind that you will have a visible indentation in these places.

3) Try to maintain a uniform wall thickness throughout your part. This helps prevent voids, warpage, and molded-in stresses. It also facilitates proper melt flow. To avoid sink marks, try to keep ribs or internal wall features around 2/3′s the thickness of the main wall. Also, be sure to design the part with the thinnest wall possible. The thinner the wall, the faster the cooling rate and the less your parts will cost you.

4) One way you can achieve a consistent wall thickness is by rounding all the edges. It’s good to avoid sharp corners (insufficient radius) as you design your plastic part because this will help you minimize stress concentrations and other defects.

5) Plastic part designers must also pay attention to gate location and type. Some of the choices you have include a direct sprue gating into the part, tab, fan and tunnel gates (just to name a few).  Gate type and location are important because they help determine how the plastic flows through the part.  Remember that the gate will leave a visible mark or a small vestige that may not look right in some areas or could interfere with the intended function of the part.

If you have any questions on plastic part design, please call me at 315.841.4101 or email at rbateman@chplastics.com.

I look forward to speaking with you about any design issues you might have. You can check out our pre-quote engineering checklist to get an idea of what we look at during the design/engineering phase.

Until next time,
Rollin