Plastic Injection Mold Design Considerations

mgmold1Injection mold designers and engineers have numerous considerations when planning out the best approach for the mold design of plastic components.  Plastic injection molding is used in various industries such as automotive, electronics, medical and defense, to name just a few.  When the same part is required in a high volume, engineers choose injection molding to mass produce required components with consistent quality.

Mold Design Derived from Part Design

 Every injection molder knows that in order to manufacture a quality part, to specification, you must begin with a quality tool.  Injection mold builders today utilize technology such as CAD (Computer Aided Design) and Mold Flow Analysis software to provide an accurate three-dimensional image of the desired plastic part before even cutting steel.  These tools provide advanced product and quality planning procedures, and assist the mold builder and the injection molder to work together in producing the part to specification.

Critical Elements of the Part Design

Careful evaluation of all critical dimensions is extremely important when designing a tool.   Some parts are designed with thin walls that can succumb to underfill, or a hole that must be within strict tolerances per customer specifications. Knowing up front where the critical dimensions, and required strict tolerances lie is of the utmost importance when designing a tool.  Some tolerances can be as tight as + or – .001 of an inch, the width of a human hair!  When carving steel from a mold to meet these tight tolerances, it is important to get it right the first time.

Mold Design is Influenced by the Molding Environment

A mold designer must know what specific type of press the mold will run in and the properties of that press such as whether it has a vertical or horizontal clamping system.  A vertical press requires shuttle molds with multiple B halves, and is typically used in over-molding, also referred to as insert molding,  which is molding plastic around an object typically made of either plastic or steel.

The most common type of injection molding press has a horizontal clamping system where both halves of the mold open and close on a horizontal mounting system,  and parts fall into a bin below the mold when it opens and ejects them.

Most injection molding presses have water fittings and lines to run through the mold for instant cooling to aid in the setting of plastic, reducing cycle time.  The placement of fittings for cooling systems, electrical connectors and wiring is an important consideration for mold designer to ensure that the mold will fit and work properly in the press.

Michiana Global Mold is an ISO9001:2015 Registered injection mold designing and building company.  We have been supplying custom precision injection molds to various industries including automotive, medical, electronics and defense for over 52 years.  Contact us today to see how we can assist you with your plastic injection mold designs.  



Plastic Injection Mold Designs Requiring Cam Action and Lifters

Engineers have many factors to consider when it comes to plastic injection mold designs, including cam action and the ejection system.    Once a mold designer has evaluated all geometric tolerances on the part print, they will typically create a CAD (Computer Aided Design) drawing of the part to aid in the design of the tool.  While reviewing part requirements and the tooling necessary to mold the part, it will become apparent if any Cam Action, or specialized ejection system is necessary.

What is Cam Action

Cam action refers to the mechanics necessary to create an undercut feature, a hole in a part would be an example.   Cam action occurs on sliding plates that would slide in when the plastic is molding around it to create the feature such as a hole, then it must slide back out in order for the part to eject properly.  If the pins or mechanics that molded the feature like a hole did not slide out of the way, the part would be lodged on that pin and would not fall out.  A cam device will pull the side-action mold surface out of the way to allow ejection from the mold.

cam-action-1-minPictured is an example of cam action; the sliding plates have barrel like rods attached to move in during the molding process creating holes in the part.  They slide back out when finished for proper ejection.

cam-action-2-minThis photo shows cams in a closed position, while molding the hollow geometrical shape of the part.

Lifters and the Ejection System

The ejection system is what pushes the part out of the mold after a fully formed plastic part has been molded.  In some instances, some help might be required for proper ejection.  This is where lifters would be included as a mechanism in the ejector system.  A lifter is an angled feature that is part of the ejector plate system, and is activated upon ejection.

The ejection system has several considerations during the injection mold design.  The ejection pattern and stroke of the press must correspond with the mold design.  Proper location of ejection pics is crucial to properly eject the mold without damaging the finished part.  In some instances, lifters are the only option to ensure proper ejection.

lifter-example-iso-view-cut-away-1An example of lifters assisting with ejection


Michiana Global Mold is an ISO9001:2015 Registered injection mold designing and building company.  We have been supplying custom precision injection molds to various industries including automotive, medical, electronics and defense for over 52 years.  Contact us today to see how we can assist you with your plastic injection mold designs.  


Injection Mold Makers and the Automotive Industry

QC Plastic

Automotive injection mold makers have enhanced the auto industry for decades now, and for good reason.  Injection molding provides consistency, high volume and low cost. It takes an injection mold maker with speed, efficiency, and a main focus on quality and continual improvement to supply automakers with satisfactory product, service and price.

Advanced Product Quality Planning (APQP)

Automotive injection mold makers must practice APQP to satisfy the requirements of automakers today.   During this process the cross functional team reviews the product and process design and development, product validation, and assessment with corrective action.  This ensures that any changes are identified, improved design and implementation techniques are addressed, and resources are allocated correctly.  APQP is a vital step for automotive injection mold makers.

ISO 9001:2015

Automotive injection mold making companies are well familiar with the quality standards established by ISO9001 and ISO/TS16949, which is the globally recognized quality management standard for the automotive industry.

ISO Registration brings together standards from across the United States and all of Europe and provides a framework for best practice with regards to the design and manufacture of products for the automotive supply chain. By following these policies, automotive mold makers are continuously evaluating their products and processes for current effectiveness, and areas of improvement.

Total Customer Satisfaction

Injection Mold makers today must practice continual improvement in all processes in order to achieve total customer satisfaction. In the Automotive industry, you need a mold builder to be responsive and act quickly, while considering all options and offering the best tooling practices to the automotive customer.


Responsiveness to any and all issues, engineering changes, documentation and sharing cost reduction initiatives are all standard practice for the experienced automotive injection mold maker.



Michiana Global Mold is Registered to ISO 9001:2015, implementing our Quality Policy throughout the organization with top down management involvement.  We have been an experienced injection mold supplier to the automotive supply chain for over 52 years.  Contact us today to see how we can assist you with your automotive mold making needs. 

History of Plastic Injection Mold Making

Simulation Importance

Plastic Injection Mold Making has been around since the late 1800’s when a man named John Wesley Hyatt first invented a way to inject celluloid into a mold to make billiard balls.  In 1872, John and his brother improved the process and patented the first injection molding machine, which was quite primitive by today’s standards but the concept of injecting plastic through a heated cylinder into a mold was born.  Plastic injection molded parts grew in popularity during the 1940’s as World War II created a huge demand for mass-produced, inexpensive products.

In 1946, James Hendry built the first screw injection molding machine, revolutionizing the industry.  Plastic Injection Molding has evolved over the years and today this manufacturing process supplies products for all industries including consumer, toys, plumbing, packaging, construction, automotive, aerospace and medical.

Part Design

As mentioned above, a wide variety of parts are made out of plastic and more and more parts that are currently made of another material are moving to plastic as a more economical option without jeopardizing part functionality.  For example, law enforcement and military agencies use plastic bullets for target practice, gun parts that were historically made of metal are now being molded in plastic.

Plastic has the rare ability to take the shape and form of almost anything you want it to be.  Parts can be molded with glass filled nylons for added durability.  Some plastic parts are used in engine and braking systems in automobiles and can withstand extreme temperatures.  Some plastic injection molded parts feel more like rubber and are used in a variety of items.  Plastic can be colored to mold in any color desired, UV protection can be added to avoid color distortion.  Very complex moving interior parts with several precise geometric designs are usually manufactured with plastic injection molding.

Tool Design

Once a molder has the part design, the next phase is to design the tool that can produce the part.  A mold built for mass production should always be built with class A hardened steel, but some prototypes are made of less durable steel as they are interim molds.  A reputable plastic injection mold maker will help guide their customer to choose the best type of mold for the job.  In some cases, just one cavity can be completed in a full size mold to be used as a prototype, allowing time to perfect the process prior to building all cavities in a multi-cavity mold.  Michiana Global Mold uses only Class A steel for the majority of their tool builds.

Michiana Global Mold’s engineering mold designers and tool makers can help to guide the customer throughout the mold build phase.  Using CAD software along with decades of experience, Michiana Global Mold knows the best way to tackle even the most complex of tool designs, specializing in injection molds for the automotive industry. 

Horizontal and Vertical Plastic Injection Molds

The majority of injection molding machines are horizontal, which means the mold opens and closes on a horizontal path.  Molten plastic is injected into the mold along the horizontal path through a heated barrel and screw.  When the mold opens and the parts eject, gravity assists with the parts falling out of the mold to the staging location.  These presses can often run without an operator once the mold is set and the process is running smoothly.  These are less labor intensive than vertical molding machines, which usually require an operator or a robotic arm.

Vertical presses are used to mold plastic around an insert of another type of material, usually steel or another hardened part.  This process is referred to as overmolding, or insert molding.  In this type of press, the mold open and closes on a vertical path, allowing the operator to reach in and grab the parts out of the cavities, and load inserts in cavities to prepare for the next overmold cycle. 

Michiana Global Mold. is a plastic injection mold maker with extensive experience in both horizontal and vertical molding.  With a wide selection of state-of-the-art milling centers, we’ve got what it takes to construct quality complex molds, on time and in budget. 

Michiana Global Mold has been in the plastic injection mold making business since the 1962, and employs a cross functional staff with extensive knowledge in part design, tool design, and the molding process regardless of the type of mold, resin, or press needed.  Contact Michiana Global Mold today to see how we can reduce your plastic injection molded project costs.



What is Precision Injection Mold Making?


Not all injection mold making is precision injection mold making.  Some examples of products that do not require such precise molding would be toys, bottles, combs and other miscellaneous items that do not necessitate a stringent level of quality.  Products made for industries such as Automotive, Aerospace, and Government / Military and Ordnance will demand the expertise of a precision mold maker.

Experience is Necessary

Precision mold makers must be familiar with meeting tight geometric tolerances, as narrow as +/- .001 of an inch.  Experience with the plastic injection molding process, especially tooling, is required for a molder to accurately meet rigid tolerances.  Some parts for the above mentioned industries are quite complex with several gates and cam action occurring in the mold.  Expertise in complex molds is required for precision work.


Automation is also a necessity to consistently meet meticulous requirements.  A process monitoring system is a software program with sensors attached to each press that monitors things such as the pressure, temperature, cycle time and shots molded.  The sensors work with a computer program to keep track of all molding information for each press, contains a scheduling module, and stores all pertinent information for each production run.  While molding, If any of the critical settings should falter out of an acceptable level, an alert system would sound and let the process technicians know to check the process and make any alterations before molding defective parts.

Material Management

With so many different engineering resins to choose from, there are a number of different molding conditions that apply to specific situations.  Some materials are molded with water lines cooling the process, and yet other materials require a hot temperature that can only be reached with a hot oil. The hydrolysis (water content) of the material will also affect the molding process.  Some projects require a complete drying of the material to achieve optimal results.

Controlled Environment

The molding environment must be controlled to maintain a consistent process. Temperature affects the molding process in several different ways, and the experienced precision injection molder knows how to maintain consistency with maintaining a controlled environment.

Quality Practices

Precision Injection Mold Making for demanding industries requires the company to follow necessary quality procedures.  Michiana Global Mold is registered to ISO9001:2015, providing assurance that your mold will meet required tolerances.  These quality standards dictate how a mold maker performs all day to day operations, not just the mold making process, and are enforced from top management down, practicing a stringent quality policy throughout the entire organization.

By practicing quality control procedures such as Statistical Process Control (SPC), and Advanced Product Quality Planning (APQP), Michiana Global Mold  provides customers with required data to support required specifications.

Value Stream Mapping (VSM) is performed for optimal efficiency and cost reduction initiatives are shared with customers.

If your project requires precision injection mold making, consider partnering with Michiana Global Mold to add value to your supply chain.

Thermoplastic Molding


Injection Molding with Thermoplastic Resins

Thermoplastic molding refers to the process of injection molding thermoplastic resins.  Thermoplastics is a type of polymer that melts and becomes pliable when reaching a certain temperature, allowing it to be molded into various forms.  This type of polymer can also be ground up and reused after hardening, as opposed to thermoset polymers, which cannot be melted and used again.  The third type of polymer is elastomer, which can also be thermoplastic, in which case this type of material is referred to as thermoplastic elastomers.  Thermoplastic resins are the most common type of material used in the injection molding process.

The Molding Process

The equipment required for thermoplastic molding is the same: a press, a steel mold, and plastic resin.  The resin is poured into a hopper on top of the press, and is then drawn into the press where it is heated in a barrel and injected into a steel mold where cavities carved out by journeyman mold makers form the molten plastic into the shape desired.  The steel mold is usually equipped with water lines running through it to cool the parts before the mold opens and parts are ejected.  Each time the mold opens, molds parts, and ejects them is called a cycle.  The typical injection molding cycle is measured in seconds.  Decreasing the cycle time can lead to improvements in efficiency and the bottom line, as long as it does not jeopardize the functionality of the part.

The Mold

The mold is the steel frame that contains the carved out cavities to actually form the part.  Every injection molding job requires a steel mold to form the molten material into a usable functional part.  There are different types of molds for different applications, but the most common is a class A hardened steel mold, capable of producing hundreds of thousands or millions of parts without wearing out. 

For the typical thermoplastic molding process, a steel mold will run in a horizontal molding press, meaning the mold will open and close on a horizontal plane.  In this case, when the mold opens and ejects the parts, the runner is also ejected.  The runner is the residual molten plastic that hardened in the channel getting the plastic to the cavity in the mold.  This is true of a cold runner mold, which is the most common injection mold.  A hot runner mold, in contrast, injects plastic directly into the cavity from a nozzle, and therefore has no runner.  A hot runner mold can assist with automation, but it is more costly than the more common cold runner mold. 

Equipment Required for Automation

While the necessary equipment is the same, a molder can invest in auxiliary equipment to automate the process and run parts without an operator, and sometimes even in a ‘lights out’ environment.  A vacuum conveying system sucks the plastic resin while in pellet form from a drum or gaylord into the hopper on the press.  As long as enough resin material is in the drum the conveying system will automatically supply a steady stream of thermoplastic resin into the press.  There are ways to regulate the amount of pellets drawn into the hopper at a time.  Some molders even have ways to measure the moisture content of material, and dry it accordingly before it enters the press.  Some molders use a moisture analyzer when required. 

Sprue Pickers Assist with Automation

When a cold runner mold is used in a horizontal press, the runner will eject with the parts and either drop to a bin below, or be grabbed by a robotic arm called a sprue picker.  A sprue is another term for a runner.  Sprue pickers assist in the automation process because it separates the parts from the runners, allowing the parts to collect in a tub by themselves and not need to be sorted or separated from the runners. 

Process Monitoring Adds Consistency and Reliability

A Process Monitoring System should be utilized for automated molding as it will monitor, as the name implies, the process as it is happening.  If something began to run out of spec, such as temperature or pressure, an alarm would sound to alert a technician.  These monitoring systems also function as material resource planning software, allowing the user to input specific job information and schedule production. 

These are some of the ways a molder can automate the injection molding process. If precision parts manufacturing is required, automation could assist to provide to a consistent and reliable process. 

Contact Michiana Global Mold today to see how we can reduce costs on your plastic part requirements.

Resin Injection Molding

3D printing

Molding With Plastic Resin

Resin injection molding is the manufacturing process of molding raw plastic pellet into usable parts.   Thermoplastic resin is the most common type of plastic used in the polymer molding process.  The resin, or plastic pellets, is used by injection molders to make parts for a wide variety of industries.


Custom injection molding is the process used by custom molders to make parts that are designed by others, typically engineers in the Automotive, Aerospace, Consumer Electronics, or Medical field.  Injection molding is also used for the Furniture, Construction, and Toy industries, although precision molding is required for the former mentioned industries requiring a high level of quality with tight tolerances.


Each resin has a melt temperature when it becomes pliable, which allows it to flow through an injection molding press, into a barrel and screw, where it is injected with pressure into a steel mold forming the desired parts.  After forming, the mold ejects the parts and closes again to prepare for another cycle.


Characteristics of Thermoplastic Resins


Thermoplastic resins have a unique ability to be strong and durable, yet also lightweight which makes is a desirable material for several functional parts. They can be reinforced with glass filled polymers, or they can have a rubber like appearance, and several variations in between.  They can be made into virtually any color, size or shape.  This flexibility is the main reason that plastic resins are the material of choice for supplying various industries with necessary functional parts.  Some examples:


  • Polycarbonate
  • Polyethylene (low or high density)
  • Polyethylene Terephthalate (PET)
  • Polypropylene (Acetal)
  • Polyphenylene Ether (PPE)


The experienced molder has all procedures in place to provide full traceability throughout the resin injection molding process up to and including shipment of quality parts that meet or exceed customer specifications, along with proper documentation.  Contact Michiana Global Mold today to see how we can help you with your injection molding needs.