Injection Mold Design for Engineering Resins

Thermoplastic engineering resins are the most common type of plastic resins used in the injection molding process.  With many different types of plastic resins each with their own unique properties, it takes great care and consideration to properly design and construct a mold for use with thermoplastic resins.   These highly useful polymer resins have varying properties of elasticity, resistance to temperature, corrosives, shrinkage and right down to the exterior finish such as a matte or a glossy finish.  

Shrink rate is a very important property of thermoplastic engineering resins used in injection molding, as the cavities must be carved out to accommodate to this shrink rate.  If shrink rate is not accounted for properly, a part may shrink too much after cooling and deviate from customer requirements. Knowing the cooling and shrink rate of the polymer resin used for any molding process is of the utmost important to the journeymen mold makers constructing the tool.  

Cooling rate is also important for the part to become completely solidified prior to ejection.  Cooling rate must be configured into the injection molding cycle time, to ensure proper cooling and ejection without damaging the part.  

Each polymer resin will have a MSD sheet, Material Safety Data sheet along with material specifications clearly defined in each numbered lot of all thermoplastic resins.  If working with a new material, a mold designer may prefer to use Mold Flow Analysis, for a computer simulated demonstration of how the plastic material will melt, flow and fill.   Predicting the flow of thermoplastic resins prior to cutting steel is vital for accurate geometrical tolerances in the final product.  

Even with a material spec sheet which is necessary, nothing helps a skilled mold designer more than experience.  Skilled mold design engineers are very familiar with the various properties of engineering resins allowing for precise mold construction with even the most specialty of molding resins.  

Michiana Global Mold is an experienced mold design and construction company, with vast experience with various thermoplastic resins used in injection molding.  We employ highly skilled journeymen mold makers and expert design engineers to satisfy even the most demanding of customer requirements.  We tackle the complex mold designs that other companies shy away from.  For complex, precision molds that must meet tight tolerances, contact Michiana Global Mold today for superior mold design and mold making services.

Contact Michiana Global Mold today to speak with one of our skilled mold designers and learn how we can assist you with your next injection mold making project.  We are an ISO9001:2015 Registered mold making company with vast experience constructing custom, precision injection molds using various thermoplastic engineering resins.  

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Maintain Molding Specs with Preventive Mold Maintenance

The cost of an injection mold is usually the largest part of an investment into a plastic molding process with the exception of the molding press itself.   Capital equipment requires maintenance, with a preventive maintenance plan typically in place for all equipment to keep machinery and equipment running at optimum performance levels and to avoid costly repairs.  

The injection mold itself is no different, operating at optimum performance when a regular preventive mold maintenance routine is performed.

Each injection mold is unique to a particular program, and may be either a cold or hot runner tool, with single or multi cavities.  Some injection molds run only a few times a year to produce a production run then store for a while before it is needed again, and some molds supporting high-volume requirements run continuously in the press.  

Performing preventive maintenance on these high-volume molds is critical to consistent part production within customer specification.  The material the used in the molding process has great impact on the steel mold.  A glass filled nylon, for example, will put a lot of wear and tear on the steel vs. a simple polypropylene material.

Take the time to determine at which cycle intervals your mold requires cleaning, and you will continue to produce high quality parts without mold breakdown.  Some preventive mold maintenance can actually be performed right there at the press, while other PM intervals require a full break-down and thorough mold cleaning.

Preventive maintenance is vital for mold performance, and to meet production requirements.  Take the time to determine the optimum mold maintenance regimen for your injection molds, and provide consistently molded parts within customer specifications.  

Michiana Global Mold is a a valuable supplier to the automotive industry, providing complex, precision molds with our ISO9001 Quality Management System.  Contact us today to learn about our rebate program and to how we can save you money on your injection mold requirements.  

How to Source Injection Molds Overseas to Save Money

Figuring out how to source quality injection molds overseas with an injection mold maker in China can be a daunting task.  This endeavor can end up costing you more than it would be saving if not implemented correctly.  How do you know the quality of steel and craftmanship that this foreign company will put into making your molds?

When providing a competitive foreign quote depends upon landing that big contract or losing it, don’t leave this huge business endeavor to chance.  Work with a domestic mold making company who can provide overseas sourcing, and overseas pricing, with the same domestic quality and service your project demands.

Offshore Mold Sourcing from Domestic Provider

Michiana Global Mold is a mold making company located in the Midwest, USA, with a business partner in China to provide the same quality in complex injection molds as our domestic locations.  Both facilities are ISO registered, following a strict quality policy in mold design and construction.  With our offshore mold making partnership, we take care of all overseas communication and quality inspections for a hassle-free transition for you.  With one domestic customer service contact, you will have tool status updates and assurances of quality with on-time delivery.  

Our Chinese mold making partner, Modular Molds, uses only North American and German Steel to construct molds built to customer KPC’s.  We supply Initial Sample Inspection Reports (ISIR), with final inspection conducted at our domestic location for complete assurances to full print specification.  

Michiana Global Mold has more than 50 years of experience designing and constructing complex, precision tools.  We tackle the challenging molds that other mold builders shy away from.   WE are a full-service mold making facility providing prototypes, insert cavities, cold-runner and hot-runner tools,  three-plate tools and shuttle molds.   Download our FREE Guide to Sourcing Your Tools in China, and let Michiana Global Mold assist with your offshore mold sourcing project.

Michiana Global Mold is a leader in plastic injection mold making, serving the Automotive and various industries since 1964.  We offer high-quality, precision tooling from our domestic or overseas location, on time and to your specifications.  Contact us today to learn more about our offshore mold making capabilities.  

Precision Injection Molds Meet Customer Specifications

Injection mold designs today must meet tough customer specifications, calling for critical fill areas with precision mold designs.   Careful planning must be taken when designing complex molds for critical applications, ensuring consistent packing and filling to tight geometric tolerances.  A qualified mold design engineer has several important considerations when beginning a complex injection mold construction, beginning with a carefully planned mold design.

CAD/CAM for Mold Design

Computer aided design and manufacturing is a valuable tool for injection mold designers, providing accurate 2D drawings and designs to meet customer specifications.  The use of CAD/CAM is beneficial when constructing molds for any industry, especially when designing and constructing injection molds for the automotive industry.  

Unigraphics and SolidWorks are two of the most technologically advanced software design programs used to satisfy the complex demands of the automotive industry.   Mold Flow Analysis is another valuable tool to identify potentially challenging fill areas, especially when using a specialty resin that may be unfamiliar to the molder.

These computer simulations are part of a thorough Advanced Product Quality Planning (APQP) set of procedures which ensure a successful mold launch.  APQP procedures are critical to the planning phase as following a detailed set of procedures identifies any issues with resin, geometric challenges such as a thin wall or critical dimensions that must remain within +/-.001” for proper functionality.  

Michiana Global Mold utilizes CAD/CAM software as part of our thorough APQP procedures, to ensure a quality constructed mold for even the most complex of mold designs.  As an ISO registered injection mold making shop, we are experienced with providing a quality mold made to customer specifications, on time and within budget.  We work closely with our customers to develop a successful mold launch to meet even the strictest of specifications.

Contact us today to speak with a knowledgeable design engineer, and Download our FREE Book on Design Considerations for Different Molds.  

Michiana Global Mold is an injection mold design and mold making company, constructing precision molds to various industries since 1964.  We are an ISO registered injection mold making facility satisfying the strict requirements of the Automotive industry with high quality precision molds.  Contact us today for a FREE design consultation.  

Choose the Proper Gate Location in Injection Molds

The gate is the mechanism that allows the plastic resin to flow into the mold, and every plastic part design must take careful consideration of the type and the location of gates.  There are various styles of gating mechanisms typically used in injection molding, and each style will have an effect on the finished product.  The style of gating chosen can affect the visual appearance of the part, the likelihood of warping or sink marks, and proper packing to meet dimensional tolerances.

 

Avoid Defects from Gate Location

 

To avoid defects when processing, place your gate location at the heaviest cross section for maximum fill and packing to avoid sinks and voids.  Experienced mold designers will also know when to consider adding a second gate location, which may be necessary in complex geometrical shapes to obtain proper fill throughout the part.  

 

The location of the gate should allow for automatic or manual de-gating, designed with the minimal length of flow path to minimize visual flow marks.   In cold runner molds, the part is usually ejected attached to the runner and gate, de-gating removes the part from the runner system.  Some processes include automatic de-gating with robotic arms that grab the runner out of the mold separating it from the part or parts.  

 

Gates in Hot-Runner Tools

 

There are basically two types of gating systems used in hot-runner tools, where the plastic is injected directly into the cavity to avoid runners altogether.  In a hot-runner tool, the gate may be either a thermal (or hot-tip) gate, or a valve gate.  The hot-tip gate solidifies the resin at the tip nozzle immediately upon high pressure injection into the cavity, stopping the flow of plastic to the cavity.  

 

A valve gate is used when the plastic may not solidify completely upon injection, and therefore a valve slides over to cover the nozzle tip and stop the flow of resin.  Either type is effective and cost efficient when used properly in a hot-runner system mold.  

 

Michiana Global Mold is experienced with constructing cold and hot-runner tools, with various styles of gating mechanisms involved.  We are skilled with determining the optimum gate location for precision molds required to produce complex geometrical parts.

 

Michiana Global Mold has been exceeding customer expectation with high performing injection molds since 1964.  We have vast experience with all types of molds and mold base components. Contact us today for a FREE design consultation and to speak with one of our knowledgeable design engineers.  

 

Plastic Injection Part Design with Ribs and Bosses

Ribs are often used to add strength and stiffness to plastic parts in critical areas or geometric designs where thin walls exist.  This makes the part stronger with added support but can also cause sink marks on the exterior side of the part, where the rib comes together to meet the main wall in the part design.  When using ribs to add support, remember the general rule that the rib should not be more than 60% of the wall thickness.  Adding ribs to an injection mold design will increase costs, and may require EDM processes.  

 

Working with an experienced injection mold manufacturer will give you the best value for your investment.  Skilled journeyman mold makers and experienced injection mold design engineers will have the best knowledge of where to place ribs for added support and how this will affect the tool design, and the cost.

 

Mold making companies today can provide you with a two-dimensional computer aided design to show you exactly how your injection mold will produce the required plastic part, and alert you to any problematic areas ahead of time.  

 

Bosses are a very common feature in many plastic parts, and comes from the word emboss, which means a raised stamp or design, standing out on the surface.   Bosses that are designed with too thick dimensions can cause sink marks similar to the use of ribs.  Utilizing the proper ratio of ribs to bosses a molder can reduce or eliminate unsightly sink marks caused by either feature.  

 

Ribs used to connect boss areas to a side wall can add strength while avoiding sink marks.  Sharp corners are another area where excessive stress can concentrate and adding small radii feature in this area can strengthen the corner and reduce excessive stress.

 

Michiana Global Mold is a full-service mold design and construction company, with vast experience in all types of molds.  We offer an ISO registered Quality System, state-of-the-art domestic mold building facility with off-shore partner, and decades of experience with precision, complex tooling.  Contact us today for a FREE design consultation and to speak with one of our highly skilled design engineers.

Plastic Part Design to Avoid Sink and Warp

Plastic injection mold designers must consider the resin chosen for the part manufacturing when designing the mold as this plays a very important role in meeting part specifications.  One characteristic of the plastic material that requires careful consideration is the cooling rate compared to the geometry of the part.

 

What is Sink

This plays an important role in the likelihood of parts developing sinks or warps, and can have significant consequences on successfully molding parts with consistent results.  The cooling rate is extremely important because as the part begins to cool it will always begin at the mold surface and move inward, toward the center.  If the geometry of the part is such that the part is too thick, the center area of the part will not solidify quickly enough.  This center stays molten long enough for it to cause stress on the area already solidified, pulling downward towards the center and leaving a sink mark on the outer surface.  

 

Avoid Sink in Plastic Parts with This Rule of Thumb

 

Ribs are used to add strength to plastic parts in thin wall or critical areas, but can also cause sink marks on the exterior side of the part.  When designing plastic parts to avoid sink marks, remember the basic rule to keep the thickness of the rib somewhere around 60% the thickness of the wall.  Following this rule of thumb should help to avoid sink marks during the cooling process.  

 

What is Warp

 

If a plastic part design includes areas of uneven wall thickness, stress can develop during the cooling and solidifying stage.  If this stress is excessive, warps will occur where thinner sections solidify faster than thicker sections.  

 

Avoid Warp in Plastic Part Design

 

When undue stresses due to transitions in wall thickness occur, plastic part designers can combat this by using a ramp.  Designers also use gussets in corners of some geometric areas to help prevent warping.  

 

Michiana Global Mold is an injection mold design and construction company with extensive experience in designing precision tools for complex injection molded parts.  Our skilled designers have vast knowledge of injection molding with various resins, and designing a mold to avoid common pitfalls in manufacturing.  Contact us today for a FREE design consultation and to speak with one of our knowledgeable engineers.