Tag Archives: plastic injection molds

Injection Mold Making Technology

Injection molding is the mass producing of plastic parts with a steel mold, an injection mold, designed with cavities to mold the desired part.  Injection molding uses thermoplastic resins, also called polymers, typically in a raw pellet form, that melt and flow into the cavities in the mold, forming the part, then it is ejected once it hardens.  The time that it takes for the mold to close, plastic to flow into the mold, the polymer to set and eject upon mold opening is called the cycle time.  Injection molders are always looking for ways to increase the cycle time, as time is money and when you can mold a part faster, you can mold more per hour, per day and per week.  

A skilled injections mold maker will have the knowledge to design the mold with the most appropriate attributes to reap the best cycle time while still delivering the desired part to the customer specification.  Michiana Global Mold is accustomed to constructing complex, precision injection molds within +/- .001”, which is about the thickness of a human hair.  

Injection Mold Making Equipment

Injection mold makers are well familiar with the precision equipment used to carve out steel cavities, forming a perfect plastic part.   Computer aided design, and computer aided manufacturing (CAD/CAM) equipment is a key tool for designing a perfect tool.  The designers at Michiana Global Mold use Unigraphics CAD/CAM software to design the mold fit for producing a desired part.  This alerts the mold maker and the injection molder to any critical areas such as thin walls or a critical dimensional tolerance that must be met, prior to cutting steel.  

Milling machines, conventional EDM and wire EDM machines are a necessary tool, along with high speed CNC machines, drill presses and grinders.   Michiana Global mold, located in Mishawaka, Indiana with an offshore mold making facility in China, utilizes all of these mold making equipment tools, and more.  We have over 50 years of experience constructing complex tooling for demanding industries such as the Automotive industry where 0 ppm (parts per million) defects is the norm.  The key to a quality plastic injection molded part, is a quality injection mold.  

No one understands this better than Michiana Global Mold, your one stop shop for mold making and tooling services.  We do everything from constructing insert cavities and prototypes to full service high volume precision production tools.

Michiana Global Mold is Registered to ISO9001:2015, delivering custom injection molds to a wide array of industries demanding high volume long lasting performance with the best available pricing.  We offer rebates on multi-tool programs and discounts with offshore molding options.

Contact us today for a FREE design consultation, and to see how Michiana Global will provide value added services in your supply chain.

Injection Mold Designs for Various Molding Environments

 

When designing plastic injection molds, there are several factors to take into consideration including the molding environment in which the tool will run.  Of the utmost importance in mold design is the injection molding press specified for the production operation.  

Some presses have either a vertical or horizontal clamping system.  A vertical clamping system is typically used for shuttle molds, also referred to as insert molds, and is used for molding plastic around an insert usually made of plastic or steel.  The clamping system will open, allowing an operator to place an insert in the bottom half of the mold, prior to closing allowing plastic to flow around the insert.  This process is used to put a plastic or rubber like coating around an object such as knives for example, or electrical wiring harnesses requiring a housing to fit around a wire assembly.  Shuttle molds for vertical clamping presses will have at least two bottom (B) halves so that the molding is occurring on one side of the press while an operator is loading inserts on the open side.  This allows for maximum production even when an operator is required.

The typical injection mold will have a horizontal clamping system, opening on a horizontal plane and allowing parts to fall below into a bin or straight onto a conveyor belt when ejected.  Some horizontal molding operations are fully automatic and do not require an operator, once the mold is set in the press and proper parameters are set.  This is a very efficient method of molding, and several molders utilize this type of operation in a lights out automatic environment.  This, of course, requires a quality crafted precision tool to ensure a consistent molding process.  

The placement of water fitting and hoses is also of equal importance, as these lines cannot be in the way of the mold operating in the press.  The tonnage and clamping pressure of the press is needed when designing the mold, and the barrel capacity is required to ensure production requirements can be met.  Download a FREE copy of our book “Design Considerations for Different Molds” for more information.

Michiana Global Mold has over 500 years of combined experience designing and building precision custom molds for various industries. Contact us today to speak with one of our knowledgeable engineers for a free quotation on your mold building requirements.  We can custom design molds for your applications, regardless of your molding environment.

Michiana Global Mold is an ISO 9001 Certified Company

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Michiana Global Mold is an ISO 9001 Certified Company providing full service design engineering capabilities and custom injection molds since 1952.   Implementing the Quality Policy throughout the organization, with Top-Down Management Involvement, MG Mold believes in empowering all employees by providing equipment with technological advances to complement the vast  experience of our skilled staff.

This combination of experience and technology enhances the skills of our expert engineers, mold designers and journeyman mold makers, resulting in dedicated functional team.

We maintain a capital investment program providing modern equipment with improvements in efficiency. Continual improvement projects are performed at regular intervals to provide our customers with quick turn-around on quality precision molds, no matter the size or complexity.  This investment in equipment and efficiency allows us to share in cost saving efforts and offer rebates to high-volume customers.

Michiana Global Mold is an ISO 9001 Certified Company in two locations, domestically located in the Midwest United States, and overseas at our off-shore mold building facility in China, our partner company Modular Mold Solutions. This allows  us to provide both semi-finished and fully finished molds at an economical price, saving up to 40% on your tool package.   This savings can be realized on all tool types: Prototypes, Production and Insert Molds, Hot Runner and Cold Runner Molds, Shuttle and Over Molds, Unscrewing Molds, Collapsible Core Molds, and 3-Plate Molds.

Michiana Global Mold is an ISO 9001 Certified Company, implementing our Quality Policy throughout the organization with top down management involvement.  We have been supplying top-quality, custom injection molds for over 52 years.  Contact us today to see how we can assist you with your injection mold building needs.  

 

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.  

 

Thermoplastic Molding

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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.

Precision Parts Manufacturing

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Industries That Require Precision Parts Manufacturing

Precision Parts Manufacturing supplies several industries with critical components.  Aerospace, Automotive, Military / Ordnance, Medical and Consumer Electronics are just a few of the areas where a precision parts molder is a valuable supplier.

The majority of molded critical components are made by the precision injection molding process, using thermoplastic resins.  Engineering Resins are a group of thermoplastic materials that combine great strength with light weight to be a desirable material in a wide range of conditions, and still be economical.

Precision Molding Process

The quality of a final critical component from the precision parts manufacturing process depends on several parameters.  Three factors that greatly impact the quality of a precision part are the manufacturing parameters, the material characteristics, and the mold design.

Manufacturing Parameters

When a precision injection molder is presented with a part print, they must determine the best size press to run the parts in taking the press attributes including tonnage, and clamping pressure into consideration.  They must also consider the type of tool to build, and the molding conditions that would yield the most optimum processing conditions.

Auxiliary equipment must also be considered.   When a precision molder can use automation such as sprue pickers and conveyors, they can maintain a consistent process and reliably produce quality accepted parts.

Determining the optimal parameters for the molding process is necessary to ensure consistency and reliable product quality.

Material Characteristics

When choosing the best material for an application, engineers must consider all characteristics of several different thermoplastic resins to choose the most appropriate resin that will meet the strength and durability demands of the functionality of the part.

It is also important to maintain a strong relationship with your resin suppliers.  Most polymer supply companies have material experts on hand ready and willing to assist with new information, suggestions and/or simulations.

Mold Design

A quality precision injection molded part requires a quality precision injection mold.  A flawless mold is the key to reliably and consistently producing parts to customers’ specification.

In most cases, the injection molder will design the mold based on the part print received by the customer.  Molds for manufacturing precision parts can be complex and require the skills of a journeyman mold maker.  It is helpful to have journeyman mold makers in-house that will lead the tool design and communicate with the customer’s engineers during the design phase.

CAD software and mold flow analysis is used, which is an indispensable tool for any plastic injection molded part.  Mold flow analysis is an indispensable component of any plastic injection molding design project.

Quality Procedures of Precision Parts Molders

Precision Injection Molding for demanding industries requires the molder to follow necessary quality procedures.  Meeting ISO9001:2008, and compliant to TS/ISO16949, and AS9100 standards and practicing them daily is necessary for success with precision parts manufacturing.