This subject has been discussed for twenty-five years or more; which direction to choose depends on the complexity of the application and type of manufacturing one does.

The basic process of creating drawings to represent objects has been around since the days of the caveman.  In the world of manufacturing, this process began with basic 2D drawings known as “blueprints” that showed three basic views of an object: Plan, Front and Side.  If additional views were needed (inside, outside, isometric, etc.), each of these views had to be created separately.  The designer had to first be able to visualize the whole entity in order to project each of the necessary views onto a blueprint.  Others could then read the blueprint to view and understand the whole entity.

Machine operators studied blueprints and extracted the information they needed to ultimately produce a physical object that matched the views shown.  They entered coordinates and determined cutter types & sizes, drill bits, taps, etc., and then began machining.

The time required to create a 2D drawing was relative to the complexity of the part or the assembly of parts.  A very simple part could be four lines that create a square, and if you need some through holes in the corners you could add four circles.  Notes and dimensions were added as required.  Creating an assembly required multiple sketches or drawings.  This could either be done by sketching on paper or using a drafting board.  When multiple copies were needed for distribution, paper sketches were copied by hand using see-through paper whereas drafting board drawings could be duplicated more quickly by a blueprint machine.

Then came electronic 2D design with CAD software.  This enhancement allowed a company with computer monitors throughout its facility to give everyone involved access to the drawings, making hard copy paper drawings unnecessary!  Any revisions to the original CAD drawing were automatically viewed by everyone opening it on their computer.  Electronic design software presented a distinct advantage because there everyone had access to the one and only “master” CAD model.  When changes were made to this master model, everyone instantly had access to the update.  This saved the time and expense of having to manually revise multiple copies of paper drawings.

From a manufacturing standpoint, 2D electronic data can be used to generate manufacturing programs that drive a machine tool to follow a given outline.  Since it is limited to XY vectors, 2D data is sufficient for Wire EDM (Electrical Discharge Machining) and the majority of all through machining applications, holes, slots, window pockets, spline shapes.

The introduction of 3D electronic data made it possible to represent a solid object in 3 dimensions.  It includes XY and Z vectors (or IJK vectors).  The benefits of creating a 3D model are numerous.

Once the 3D model is created, it can be viewed by multiple people as if they were holding the physical object in their hands.  It is a solid body with volume, mass, internal and external features, and it can be rotated to any viewpoint allowing you to extract the information you need.  At Matrix Tooling, Inc. our designers use NX software (formerly Unigraphics).

The time required to create a 3D solid model is dependent upon its complexity, and 3D solid assemblies of multiple parts can also be created; an automobile assembly, for instance, might be used for display, sale, mechanical function, or aesthetic purposes.

The availability of 3D data has virtually eliminated the need for any 2D drawings in manufacturing, although some customers will still ask for them.  It takes considerably less time to create views on a drawing using 3D data; it’s just a matter of placing canned or custom views on a drawing that are linked to the 3D solid model or assembly.  The views are always to size and if a revision is made to the model, the drawing views are updated automatically.

Manufacturing using 3D data allows a machine operator or a CAM specialist to generate any type of machine path, limited only to the machine tool’s axis – be it 2D or multiple axis.

While 3D software packages are certainly more expensive than 2D systems, we have found that the benefits far outweigh the costs.  In our business of designing & building complex plastic injection molds, 3D design has not only helped us become a leader but will also play a critical role in maintaining our advantage.

Written By:

Hans Noack
Design Mgr.

 

 

Since we've added web conferencing several years ago, it becomes more and more evident how this tool significantly improves the design / build process as costs are scrutinized and deliveries compressed. One recent program stands out, a stapling device with numerous metal and plastic parts that were activated by a series of gears and pulleys. Our initial design review with the customer using our web conferencing program allowed us to review the entire assembly get an overview of the device with a diverse group of Matrix personnel. Representatives from our design, manufacturing and quality areas all reviewed the device from their own point of view. And with the convenience of a voip phone call, our marketing manager attended the meeting remotely. During the review, suggestions were made to the customer that allowed them to eliminate several parts by redesign of the current assembly. Parts were combined, reducing the part count in the assembly. Slightly more complicated tooling, but far less costly in the long run. The customer immediately embraced those suggestions, as their COGS target for the device was going to be difficult to achieve. The savings our suggestions allowed gave them an immediate benefit. And, during the review, a fundamental design flaw was flushed out when this group of a dozen technical people got into a spirited discussion on the mechanics of the device, which was corrected within days. And as our mold design work was firming up, we held a concurrent review of both tool and product design, which saved significant time. Mold design (ours) and device design (theirs) were being toggled back and forth, with mods to both being made as the meeting continued. A very fast and productive use of time, for sure.

 

- Paul Ziegenhorn

 

A thermoplastic injection mold is like most anything you buy in life; you get what you pay for. If you want a throwaway mold with a limited life expectancy that produces simple parts and allows for generous dimensional and flash tolerances (and may require post-molding defect corrections like flash trimming), then by all means purchase inexpensive tooling from a low-cost supplier. But if factors like part consistency, uptime, conforming to quality standards, on-time delivery, low maintenance costs, long mold life, and fewer headaches are important to you, you’ll likely want to consider buying a quality mold upfront.

An injection mold is not a small purchase to be taken lightly, even for a tiny plastic part produced by a large corporation. It should be viewed as an investment, with each running cycle giving back a portion of your ROI.

For many of the molded parts of bygone years, an inexpensive mold might have been sufficient. Times have changed though and products have become more demanding. Their geometries and resins have demanded a more complex, precise and robust mold. An inexpensive mold won’t be able to give you these parts, at least not for long. What good is a cheap mold that breaks down in the middle of a production run, fails to make in-tolerance parts, or runs slower than the calculated cycle when the customer needs a steady stream of good parts promptly and consistently?

There will always be a place for simple and cheap molds in certain applications, but if there is any complexity to the part or tool, it would be foolish to build and design based on price alone. Overseas low-cost providers are an option, but that opens up potential issues with communication. Not only due to language problems, but time zones, local customs, and general business practices can add on top of that. Logistic issues and rising transportation costs should also be considered.

Reputable mold builders stake their reputations on every mold they build. They want a robust mold, built correctly with the best materials, that doesn’t come back for repair or adjustment. They want the customer to be there if at all possible for design reviews and samplings. All the teleconferencing in the world can’t take the place of personal meetings at times. These personal meetings are with the mold maker’s technical staff and design specialists, not some sales rep or consultant for a cheap offshore mold builder.

Often, time to market is critical, and control of the project timeline is not always possible with an offshore supplier. When a cheap mold is late, produces out of tolerance parts, or breaks down, its low purchase price suddenly becomes very expensive. Many times a cheap mold that doesn’t perform like it should can end up being more costly to correct than a more expensive North American mold would have been in the first place. Losses in time and productivity are often just as costly and are even harder to recoup.

When the whole picture is looked at, you can see that in the purchase of an injection mold the old adage of “you get what you pay for” holds so true.

Written By:

Brent Borgerson
Senior Process Engineer (Older Molder)

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