2 Dimensional vs. 3 Dimensional Data – Which One is Right for You?

August 6, 2010 in Design by hans | No comments

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.

Design Review Conferencing

June 17, 2010 in Design by paul | No comments

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

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Two-Stage Injection Molding

April 21, 2010 in Injection Molding by andyz | No comments

My favorite part about working on R&D projects is that they tend to challenge you to think outside the box, try new things, and learn about the latest technologies.  One of our recent development projects involved injection molding a long, thin-walled tube (picture a miniature drinking straw) with a wall thickness that shrinks down to .0035” over its nearly half-inch length.  By comparison, that’s roughly the same thickness as a human hair.  Even after running dozens of Moldflow® studies for gating locations and flow analysis, the only thing we were confident of was that it was going to be a challenge to fill the parts out completely.
After struggling on our first sampling, the instinct was to look for higher flowing materials to help make the distance more manageable.  We started with a PE material with a Melt Flow Rating (MFR) around 50 g/10min and then moved on to a similar material with a MFR of 110.  We were expecting to see a noticeable improvement in the 110, but what we found was no appreciable difference on the fill.  It was determined that this was primarily due to leakage at the check ring / non-return valve, common to all traditional, reciprocating screw injection machines.
This brought us to one of the more interesting suggestions on the project.  We decided to sample the tool in one of Sodick-Plustech’s (SPT) micro injection machines.  This machine piqued our interests initially because of its two-stage (plunger-style) injection approach, but as we found is well-suited for this type of application for several reasons.
Like a traditional, reciprocating screw machine, Sodick’s two-stage injection technology (shown here) utilizes a small screw to melt and convey material.  But unlike traditional machines the screw is not responsible for injecting plastic into the mold (or any high speed lateral movements).  It feeds a second chamber, which is metered precisely, and then injected into the mold via a high-speed piston.  The feed screw shuts off after material is loaded into the chamber, which eliminates back-flow without the use of a check ring / non-return valve.

Photo courtesy of SPT

On this particular machine, the piston is capable of reaching injection speeds of 450 mm/s, which isn’t particularly impressive by today’s standards.  Many other press manufacturers tout injection speeds well past 1,000 mm/s.  Sodick, too, offers a high-speed/high-pressure line that boasts an impressive 1,500 mm/s injection speed, but their selling point is based more on acceleration than on speed alone.  The Sodick machine utilizes an accumulator that works with the main piston to reach maximum speed almost immediately upon injection.
The next selling point is the consistent shot sizes due to the tightly metered second chamber.  For our application, this is critical because an inconsistent fill could cause a short shot, which would be nearly impossible to detect with the human eye or a vision system during production.  On a project that could expand to a 16 or 32 cavity tool, this becomes increasingly critical to maintain good production parts.
Another positive about the machine is a more consistent melt and material residence time.  Again, the lack of a check ring helps by allowing for a more reliable first-in/first-out material path.  And since the feed screw isn’t creating excess heat via shear, the material is subject to more uniform heat profiles as it moves through the processing stages.
One last positive about the machine is the capability to swap out injection units (smaller or larger) and match them with differently-sized platen and tie bar configurations.  Matrix is running quite a few bioresorbable/bioabsorbable polymers lately which require minimal shot sizes due to the extremely high material costs.  However the molds associated with these projects are often complicated and require multiple side actions, slides, and/or lifters, so running them in a traditional micro-molding machine with a 4-inch max opening and similar small distances between the tie bars doesn’t always lend itself to the mold design.

Written By:
Andy Ziegenhorn

Insulated Runner Molds: Old Technology, but Not Entirely Obsolete

March 22, 2010 in Commodities, Injection Molding, Manufacturing Technology, Plastics / Resin by brentb | No comments

Early in the history of injection molding, molders realized the problems inherent in producing high volume, fast cycling parts of commodity resins with cold runners, especially in high-cavitation molds.  Cold runners can stick or hang in the mold and interrupt or extend the cycle; and often the cold runner being the last part of the shot to set up, can dictate the overall cycle.

It soon became obvious that “runnerless” molding was the way to go.  Early hot runners were of the internally heated (torpedo) type or the externally heated manifold hot runner.  Both were prone to leakage and hard to (especially the torpedo type) change colors with.  Predating these systems were a type of runnerless mold called an Insulated Runner.

Insulated Runners had an oversized internal runner cut into both the top clamp plate and the “A” plate.  This runner was very thick and relied on the thickness of this runner-cull to keep the plastic in a molten state as long as the molding machine was cycling.  The walls of the runner were solid with only a molten center core providing melt delivery.  These led to cylindrical drops (also very thick) and generally to top-center-gated parts.

This system needed fast, uninterrupted cycles to keep the gates open and even momentary interruption caused one or more gates to freeze off.

Startup was also tricky with these molds.  Methods included hand injection of multiple shots into the mold before going to auto, making one big shot and going to auto, or boosting the back pressure way up and extrusion filling the runner cull.

Later the gate drops were heated with a probe which made startup easier and also made keeping the gates open easier, even allowing a brief disruption the the cycle.  With very fast cycles (3 to 6 second range) the heated probe insulated runner can have a fairly small thickness and in some cases, be reground and re-used in the product.

Though sometimes a bit tricky to startup and keep running, these systems could offer advantages over not only cold runners, but hot runners as well.  These include:

  • Quick cycles
  • Less regrind and scrap, though the thick cull wasn’t generally used back in molding
  • The tool was less expensive to build and maintain
  • Less chance for melt leakage.
  • Color changes were very fast compared to hot runners, as the whole colored cull was pulled after the molding machine’s barrel was cleaned. Often color changes can be preformed in 5 minutes with less than 5 pounds of scrap
  • Even if heated gate drops were employed, fewer and less sophisticated controllers were needed.

Yes, the insulated runner is an old technology, but if you have a multi-cavity, fast-cycling job using a commodity resin like PP or PE with frequent color changes, and want a more economical tool that is easier to maintain, then consider insulated runner tools.

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Drying Bioabsorbable Resins

February 5, 2010 in Bioresins, Injection Molding, Plastics / Resin by brentb | 1 comment

Drying is an important part of the process for any product made of hygroscopic (meaning affinity for moisture) thermoplastic.   For medical implants made of bioabsorbable polymers, dryness is particularly critical.  Inadequate drying can produce a variety of problematic results.  These include:  lack of tensile properties and impact resistance, as well as varying flow characteristics.

Bioresins, much like other hygroscopic thermoplastic resins, can suffer three types (or a combination of these three types) of degradation:  thermal, mechanical or hydrolytic. In most thermoplastics these types of degradation occur chiefly during the molding process. With bioresins such as the PLA, PLG , and PGA families, hydrolytic degradation also occurs before and after the molding process.

An implantable device must decay or degrade in the body as part of the absorption process. Different materials and part designs have different rates of degradation in the body (where it is in a moist environment).  The rate of degradation and retention of mechanical properties is affected in no small degree by the way the resin was dried and how the dried resin and finished part were handled.

If a bioresin grocery bag degrades quicker than it was designed to, the results can be the bottom falling out and groceries on the ground. If an implantable device degrades quicker (or slower) than designed to, the results can be harmful to the patient. The degradation process of the implant is key to resorption in the body.

Run of the mill dryers are generally not sufficient to control the moisture as well or reach the super-low moisture levels desired for absorbable implants. Many implant molders opt for vacuum dryers or compressed air with membrane dryers.  Since most implants are small, vacuum ovens designed for lab use is another option for resin drying.  In any case, the drying schedule and temperatures provided by the resin manufacturer must be strictly followed.

In many cases, the resins must be dried to less than 0.02% (200 ppm) and the resin and finished product must be maintained dry. This requirement mandates an inert gas such as nitrogen atmosphere in any non-vacuum dryer hopper, humidity controlled atmosphere in the cleanroom, vacuum packing with a desiccant and nitrogen, and refrigerated storage of the resin prior to drying.

It is not enough to strictly follow the drying and handling procedure, the resin dryness must be well tested, documented, and controlled.  The dryness data is so important because it must be correlated with part degradation data to be able to predict implant device performance and absorption in the body.  Lost weight or halogen type moisture analyzers are relatively economical devices but should be equipped with data acquisition and logging technology.

Drying bioabsorbable resins requires specialized knowledge, methods, and equipment, but is key to successful bioresin implant molding.

Life Expectancy of an Injection Mold

December 18, 2009 in Injection Molding, Mold Making / Tool Building by brentb | No comments

Of great interest to buyers, accountants, quality managers, toolmakers as well to, of course, molders, is the projected service life of an injection mold for thermoplastics.  Many people in the injection mold industry use the SPI Mold Classifications as guides for estimating the expected life of a mold. The common classifications are:

  • Class 101

For a life in excess of a million cycles, with a hardened mold base (minimum of 28 R/C), hard molding surfaces (minimum of 48 R/C) with other details of hardened steel. Guided ejection is mandated as are other features such as wear plates for slides. Parting line locks are mandated, and corrosion resistance is suggested for cooling channels. This is the highest quality of the SPI classifications, usually accompanied by the highest price.

  • Class 102

This is specified for a lifetime not to exceed 1 million cycles. This features the mold base hardness of class 101, molding surfaces (cavities and cores) also feature the hardness specified in 101, and functional details are heat treated. Parting line locks are recommended. Guided ejection, wear plates, and corrosion resistance of water passages are not mandatory, but dependent on expected total production quantities. If expected cycles approach the maximum, then these features should be specified.

  • Class 103

Aimed at molds intended for under 500,000 cycles. These are molds for low to medium production needs, and corresponding price ranges. Mold bases are at least 8 R/C and cavities and cores in excess of 28 R/C. Any extras must be agreed upon.

  • Class 104

For less than 100,000 cycles and limited production. These are lower priced molds. The base can be aluminum or mild steel. Cavities and cores can be of the same or a metal agreed upon.

  • Class 105

These are for cycles less than 500 (prototyping only) and are very inexpensive. They can be of cast metal or epoxy.

These SPI, or Society of the Plastics Industry (http://www.plasticsindustry.org), classifications should and do take much of the guesswork out of estimating the useful life of an injection mold, but not every class 101 mold is the same, and this is true in all the mold classifications. Classifications indicate, but don’t guarantee quality.

No matter the class of mold, how the molder treats the mold can determine the life of the tool. I have seen and heard of aluminum molds that have lasted for years, indeed decades, and conversely witnessed class 101 tools rapidly turned into junk.  Much of what the molder does, or how he treats the tool will determine the life of the mold.

Never over-clamp (use more than required clamp force) the mold not only will you wear, stress, or deform the steel prematurely, you will peen closed the vents, leading to a viscous circle of more injection pressure being dictated and then even more clamp force.

Don’t neglect preventive maintenance on the tool, devise a schedule or consult generic schedules, or better yet consult a reputable mold builder. Taking the mold down for a day or two for PM can add years of life to a mold. If you don’t have in-house tooling capabilities for this you can contact a mold builder such as Matrix Tooling Inc. A great part of mold PM is disassembly and cleaning and replacing components such as springs, o-rings, and pins. Many molding shops designate a person for these relatively simple but extremely important tasks.

Don’t skimp on mold protection, sometimes called low clamp pressure. You want to be set “fat” enough to stop the mold from clamping well before a possible stuck part is crushed by the mold faces. Your press maker can train you in this if there are any doubts. Many mold protection settings can be defeated by closing the mold too fast. Never slam a mold closed. Where there are slides or other actions and angle pins, you should slow the movement before they engage. The possibility of saving a half second on the cycle here could cost days of lost production while repairing the damage that a defeated mold protection could produce.

Daily cleaning of mold faces and lubing components such as pins and slides will extend the life of any class mold. Use the right lube for the job: FDA and medical grease where required and high temp grease for hot running tools such as those running PEEK, PEI, PPS and PSU, where mold temps can exceed 400°F. Remember it is the film of grease a few thousands of an inch thick that does the job, so don’t goop the grease on. It is counterproductive and can attract dirt.

Again the SPI classifications can give the molder a good idea of the potential lifetime of an injection mold, but not all molds in any one classification are made equally. One should always have their molds designed and built by a reputable mold builder. A mold builder such as Matrix Tooling Inc. will stand behind and care for every mold the build over its extended lifetime.

Brent Borgerson
Senior Process Engineer (Older Molder)

Dryness of Nylon: an Essential Component of the Injection Molding Process

October 15, 2009 in Commodities, Injection Molding, Plastics / Resin by brentb | 3 comments

Like many thermoplastic resins, nylon has its quirks and accompanying processing considerations. One of nylon’s most notable characteristics is its affinity for water. Nylon is extremely hygroscopic, a veritable sponge, absorbing any humidity in its environment. It is an efficient sponge; quick to suck up water, and slow to give up the moisture.

Moist nylon resin affects the end product, often producing brittle or dimensionally unstable parts. Cosmetics are also affected; splay being one notable cosmetic defect that can be caused by moist resin. If the processed resin is out of moisture specs, it is essentially degraded. This is called hydrolytic degradation, and the effects and symptoms are akin to thermal degradation. Desired characteristics of many nylon parts include toughness and impact resistance. Parts produced with resin that has been sub-optimally dried can lack these traits.

Moist nylon resin can be hard to process. Nylon has a tendency to drool from the nozzle. Good heat control at the nozzle is important for molding nylons successfully and controlling nozzle drool or freeze-off, but wet resin can make this control almost impossible to achieve.

In addition to drying nylon well, it is important to dry nylon consistently. The same nylon resin dried at different moisture levels will exhibit different melt viscosities, even though the moisture levels may be within the manufacturer’s specifications. Water acts as a plasticizer; therefore wet nylon will fill more easily than dry nylon. This is reflected in peak fill (transfer) pressure and can be reflected in fill times, especially visible in a pressure limited process. For good consistent molding results, especially in a product with demanding dimensional specs, the resin moisture level should be consistent from run to run.

If nylon is allowed to stay in the dryer for too long (over the recommended time), the material can start to degrade as well.  Natural nylon may start to turn yellow.  The finished part may also be very brittle.  This is more common on nylons than most materials.

When inspecting nylon parts it is always good to allow the finished part to absorb the moisture in the air before you do your inspections.  Depending on the environment this can take a few hours or more.  Some nylon jobs require a fixed amount of moisture to be put into the poly bag that holds the parts.  This is common in the processing of nylon straps.

At Matrix Tooling/Matrix Plastic Products, we strictly follow manufacturers’ recommendations for drying temperatures and times to ensure dryness, and we have a moisture analyzer to verify the results. We have found that good, consistent drying gives consistent molding results.

Written By:

Brent Borgerson – Senior Process Engineer (Older Molder)

Patrick Collins – Molding Operations Manager

The Value of DOE in Injection Molding

August 28, 2009 in Injection Molding by brentb | 2 comments

DOE or design of experiments (sometimes called experimental design) can be a powerful tool for any molder to have in his or her arsenal.  We live and mold in a demanding era.  We must mold with tighter tolerances, less scrap, and quicker cycles than ever before.

I was brought up by my mentors to change only one variable or parameter at a time, then measure the part or observe the outcome of that change. Curing a defect or establishing a robust process was often a matter of days, weeks or more.

DOE can cut the time for defect remedy, process establishment, and process validation to a fraction of what the old “trial and error” method took.

DOE may sound complicated to many Molders, but where once DOE was the territory of statisticians and engineers, new software developments have simplified the process and interpretation of the resulting data.

At Matrix Tooling/Matrix Plastic products, we use a software package designed for injection molders.  It supports up to Taguchi Level 8 experiments.  We can focus on, say, three inputs or factors in an attempt to achieve one or more desired responses or outputs, also called outcomes.  Factors could include: mold temperature, melt temperature, injection speed, and pack pressure among others.  The response could be anything from warp, flashing, a change in physical properties, or certain dimensions. Choosing inputs and responses requires knowledge of and experience with the injection molding process. This is much more important than being a statistician.

Taguchi L8 experiments require eight runs, and each run will have changes to multiple inputs. Results are measured, noted, and entered into the software which then maps the results on various graphs and charts for analysis, including: response surface graphs, scatter plots, main effects plots, Pareto Diagrams, ANOVA and other high powered statistical tools. In short one can see graphically what parameters or combination of parameters affect the desired outcome. You may not necessarily cure the problem during the first DOE if it is a hunt for a defect cure, but you will likely be pointed in the right direction.

Aside from troubleshooting, DOE is a recognized tool for process evaluation and validation, especially for FDA requirements for the medical device industry. There are a number of methods and tools recognized for FDA evaluation: SPC control charts, capability studies, Failure Modes and Effects Analysis (FMEA), error proofing, and DOE.  Many nonconformities are the result of excessive variation.  DOE can be a great tool to reduce and control variation. Different types of designed experiments are used here to identify key input variables and one kind of Taguchi experiment actually emulates the variation that could be found in a process over time through small but structured parameter changes.

A Molder must use all the tools at his or her disposal to quickly identify key process influences and arrive at a robust process that is defect free.  DOE is a powerful tool, and astute molders should know how and when to use it.

Possibilities of Why a Polycarbonate (PC) Part Is Cracking

July 23, 2009 in Engineering/Medical Grades, Injection Molding, Plastics / Resin by pat | 4 comments

We recently had been asked by a potential customer why a polycarbonate would crack post-molding.  They had been having this issue on a specific part from one of their current suppliers.

Our first step was to ask if we could get a sample of the part and the process sheet.  After looking at the part and reviewing the process sheets we noticed the following:   First, key set points like the dryer settings were not included in the process sheets.  We saw this as a potential red flag.  With polycarbonate it is very important that the material be dried correctly with the proper equipment.  Polycarbonate requires a dryer setting around 240 degrees for four hours (following the material recommendations of course, some may vary around 250 degrees for four hours) but doing this requires a high-heat dryer.   It is always good to verify that the moisture is 0.020% or less prior to molding.

Further looking into the setup sheets we noticed that the injection pressures were all on the high side of the recommended range.  This can be a sign that the gate size or nozzle orifice may be a potential suspect.  Running the incorrect gate size or nozzle size can induce molded-in stress.

We also noticed a lack of process monitoring; the set limits would allow the press to continue to run outside the manufacturer’s recommendations.  If uncontrolled, incorrect barrel temps, pressures or screw cushion can all be reasons for in-molded stress.

In looking at the part, the molded stresses were obvious, particularly when looking through a polarized lens under strong lighting.  The stresses create a rainbow effect in the translucent material.  Our next step was to measure the gate size and we found it to be much smaller than what we would recommend for PC.

So we had plenty to consider from the start, and these are just a few possible reasons for PC cracking.  We’ve also been told by the material manufacturer that some mold release sprays can attack polycarbonate.  They even had a story about an operator whose hand lotion was found to be the culprit for cracking parts.  This is one reason we do not allow silicone mold release in the plant and insure our operators use gloves on polycarbonate jobs.

After ruling out all of the above possibilities, it’s possible that some part designs may require annealing for stress relief.  Annealing of the plastic part is the process of heating the post molded part to just below its softening point, then keeping it at the high temperature for a period of time before cooling it slowly back to room temperature.  This can relieve some molded-in stresses but isn’t a desirable solution in most cases.

Processing polycarbonate at the manufacturer’s recommendations is the key to stress-free and crack-resistant parts.  If, for any reason, you are unable to follow the recommendations you should ask yourself why and correct the problem at its roots.

Written By:

Pat Collins
Molding Operations Manager

The Three R’s of Injection Molding

July 9, 2009 in Bioresins, Injection Molding, Plastics / Resin by brentb | No comments

Plastics have long been associated with environmental unfriendliness and wastefulness of crude oil and petroleum byproducts. The advent of bioplastics (biodegradable and biocompostable plastics) which are derived from renewable sources such as corn starch or vegetable oil is helping to improve the image of plastics among those concerned with the environment, carbon footprints, sustainability, and being “green.” Bioplastics are slowly but steadily being improved, and in some cases their abilities to process and end-use properties can mimic or even surpass those of traditional petroleum based materials.

Bioplastics, aside from being derived from renewable resources, have the advantage of not releasing harmful toxins during their production, processing or degradation. Many conventional plastics can release known or suspected carcinogens such as formaldehyde or benzene during production, processing or destruction.

Growing the sources for bioplastics also reduces carbon dioxide in our atmosphere. Since the production of conventional plastics produces so much CO2 the use of bioplastics in place of a conventional plastic has a cumulative effect, with the substitution of just one ton of bio for conventional plastic having the net effect of reducing multiple tons of CO2 in the atmosphere. This not only takes into account the production methods for each type of plastic, but also the photosynthesis process in growing biomass or raw material for bioplastics. Bioplastics show great promise in reducing both our industry’s carbon footprint and impact on rising global warming.

What can plastics processors do until bioplastics are perfected in properties and reduced enough in costs to truly compete on a large scale with conventional thermoplastics? This is where the 3 R’s apply in injection molding. The 3 R’s in molding don’t stand for “reading, riting and ‘rithmetic,” but rather: reduce, reuse, and recycle. At Matrix Tooling / Matrix Plastic Products, we have been molding with bioresins, including bioabsorbables for a number of years, but as responsible members of the environmental community, we also have been practicing the 3 R’s.

Reduce: Scrap (and resin usage) is reduced through cold runner and sprue size reduction where possible without affecting moldability. In many cases we have reduced sprues and runners to the prescribed percentage of regrind allowed in the product specification. Hot runners and hot sprue bushings also have been used wherever possible. We have also thinned out wall stocks on parts where the product integrity wouldn’t suffer.

Reuse: We reuse what regrind we can and have come up with applications to use up to 100% in-house regrind. We utilize returnable/reusable packaging where possible and where allowed by the customer. We also have a closed circuit water system to reduce consumption and also filter, monitor and analyze hydraulic oil to avoid indiscriminate unneeded oil changes.

Recycle: Where we can’t reuse in-house regrind, we try to find it a good home. We sell the regrind where possible or even give it away for free if it can be used but there isn’t a paying market. Packaging is recycled also. We even collect our soda pop cans!

Matrix is serious about being environmentally responsible, using bioresins, and abiding by the 3 R’s. It not only makes environmental sense, but favorably affects the bottom line.

Written By:

Brent Borgerson

Senior Process Engineer (Older Molder)

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