What Every Product Manufacturer Should Know About Plastic Injection Molding

Injection mold tooling and part production can challenge even the most experienced product manufacturers. In some circumstances, product designers may have minimal experience working with plastics or be managing a design that requires advanced consultation.

It’s important to understand that ultimately, the goal that you and your injection molder should strive to achieve is an optimized mold for the type of plastic, part geometry and finish, desired cycle time, production volume and, of course, highest level of cost effectiveness.

Where do you begin with so many variables? These are the important aspects every product manufacturer should know about plastic injection molding.

The Process:

Plastic injection molding is one of the oldest methods of manufacturing plastics and a critical step in the development of parts for product manufacturers. It’s also a great solution for manufacturers looking to convert heavy metal parts to plastic. Explained in its simplest form, the process uses polymers or plastic resins that when heated, melted and injected under high pressure into a custom mold, will produce plastic parts to be utilized in product manufacturing.

While that process seems straightforward, it can actually be quite complex and requires a high level of experience from an injection molder partner that can cater to your unique industry needs, specifications, end-uses and time / budget constraints. The best place to start is by gaining basic knowledge of the plastic molding process.

Pricing Factors:

Injection molding is one of the most commonly used methods of manufacturing plastic parts because it can be done at a reasonable price and with the use of a large variety of materials. This oftentimes fully-automated process can produce a high rate of output that is typically more budget-friendly than alternative production options. 

Mold Price Factors 

  • Design Strategy: Have a strong understanding of your part’s end use and the requirements for volume, complexity, tolerances, surface finish, gating and molding material will allow your injection molder partner to determine the most appropriate and cost-effective solution for you.
  • Mold Size: It’s a given that larger parts will require a larger mold and generally increase cost. However, there are ways to optimize mold and part design to help reduce cost. An additional consideration is when a part’s material feed system is properly sized, the cost of the injection molded part may be reduced.
  • Offshore vs. Onshore: There are some common misconceptions regarding offshore mold production and cost savings. Oftentimes, offshore mold production does not reduce time or mold / part cost in the long run.

Not only are molds made in the U.S. generally higher quality, sometimes governmental regulations require that tooling be designed and built in the U.S.

In the case where you have a challenging mold build, working with a reputable injection molder in which you can establish a trusting relationship, will save you time and money over the life of the mold and part production. Challenging builds may include multiple cavities, moveable mold components, thin walls, complex textures, gating restrictions, tight tolerances and more.

Part Price Factors

  • Part size: Part size is a factor with larger parts resulting in a greater material cost.
  • Part design: Complex part designs result in an increased tool cost. Working with a knowledgeable design engineer to simplifying part design can lower the cost of the tool. A mold that is well-designed ultimately has lower residual costs over time in addition to lower part reject rates.
  • Material selection: There are many factors that can affect the cost of your material selection. Does the part need to withstand pressure, weight, temperature variations or elements / chemicals? Do any regulatory requirements apply? High performing and specialty resins come with a higher cost. Certain characteristics of your resin can also increase the maintenance cost of your mold.
  • Part tolerance: Parts designed with tight tolerances will require more intricate manufacturing steps which may can increase manufacturing and tool maintenance costs.
  • Volume: It’s obvious that the higher your annual volume, the higher overall cost is for part production. However, it’s important to also consider volume not only in the number of parts, but also hours of production. Parts that will be run at a higher volume, need high quality tools with possibly a higher number of cavities. That said, cost per part typically goes down as volume goes up.
  • Cycle time: Cycle time is another example of where well designed tooling and part cost go hand in hand. Fast machine cycles during the production process require well-designed tooling and a high precision build for a part to cool uniformly throughout the cavity impression.
  • Gate location: Proper gate location is a critical component to part quality. Parts that require design techniques where gates are not at the side of the part may increase tool cost.

Industry Jargon:

Plastic injection molding continues to evolve with advances in technology and resin science. Many important decisions regarding tool build, materials, maintenance and production happens during the communication process between you and your injection molder. Each party should have a strong understanding of short-term and long-term expectations which should be shared early in the design / development process.

Like any profession, no plastic injection molder is the same. While there are certain terms, keywords and phrases with implied meaning, it is helpful to have an understanding of the terminology that will be used throughout the completion of your project.

Early Design Consultation: 

Choosing an experienced injection molder that provides design consultation is one of the most important factors in your production process. Designing a plastic part for manufacturability involves many important facets that touch on all areas of part design, tooling, material selection and production. First, it is essential to build parts around functional needs by keeping design intent or the end use in mind. Consider weight reductions, the elimination of fabrication and assembly steps, improving structural components, reducing costs and getting products to market quicker.

In addition to early design consultation, working with a partner that provides the latest technology in mold flow analysis can save significant time and budget dollars. Mold flow software can be used to evaluate the design to make sure it will produce the most consistent and highest quality parts from each cavity of the tool. A virtual model of the mold is created and, using the known data and characteristics of the chosen material, the software can predict how the material will flow into the mold and its cavities. Different data points can be assessed, including pressure, fill time and melt temperature. Doing so allows for optimization of the process before tool production ever begins.  

The information provided above offers direction and recommendations for understanding the important aspects of injection molding prior to beginning your production process. Regardless of the elements you think your project requires, it is always vital to start with a thorough consultation to evaluate what will work best for your product, budget and timeline.

Injection molding is a complex process, but it doesn’t have to be overwhelming. Nicolet Plastics is here to help. Contact our knowledgeable design engineers, tooling and production experts to help you get started on your next project.

6 Considerations Before Choosing a Plastic Injection Molding Part Manufacturer

Plastic Injection MoldingThe manufacturing process can be a complicated one and there are many factors to consider when choosing a plastic injection molding partner that best suits your industry, unique products and production requirements. First and foremost, the best place to start is by gaining basic knowledge of the plastic molding process. Explained in its simplest form, the process uses polymers or plastic resins that when heated, melted and injected under high pressure into a custom mold, will produce plastic parts to be utilized in product manufacturing. While that process seems straightforward, many manufacturers need an injection molder partner that can produce highly complex parts and caters to their unique industry needs, specifications, end-uses and time / budget constraints.

These are the key factors any product manufacturer should consider when choosing a plastic injection molder:

1. Volume Specialization & Capacity:

With over 16,000 injection molders in the U.S., selecting the best molder for your part can seem overwhelming. The best place to start is by narrowing down your options based on your volume and size requirements. Low to moderate volume molders specialize in the production of parts under 10,000 units. Selecting a low to moderate volume molder may be an ideal choice if you need to quickly produce a prototype to test a part.

In addition, low to moderate volume molders are perfect for applications that don’t require hundreds of thousands of parts (such as medical devices, aerospace, agriculture and more), or bridge tooling (tooling that bridges the gap between small production runs for market testing and full-production tooling).

High volume molders specialize in jobs requiring over 750,000 parts and typically produce parts requiring small-sized molds.

2. Compliance with Specifications:

Having to compromise puts product manufacturers in a challenging situation. Regardless of the details involved, there is likely a company that can produce your part without specification sacrifices. Injection molder partners should be able to make strong recommendations based on the specifications you require without having to make significant compromises.

Recommendations should stem from the injection molder’s experience, expertise and knowledge of the latest technologies. Specification changes may include minor design tweaks, alternative resin suggestions, and other ways you can save time and money during the design, development and production process.

3. Expanded Services & Technology:

Not all injection molders offer expanded services or the technology needed to help design parts for manufacturability. Working with a molder who offers prototyping, part design services, quick response manufacturing, in-depth mold flow analysis and more – in addition to their traditional service offerings – will help you create valuable cost and timing efficiencies in regard to getting your product to market.

An important factor to note is that the greatest efficiencies with overall project time and budget happen early in the development cycle – specifically the design process. That’s why it is critical to choose an injection molder that can become involved early in the design process, understand your objectives and can predict production issues before they occur. 

4. Quality & Efficiency:

In addition to complying with your specifications, your injection molder partner should be established and committed to providing the best service possible. Answering these questions will help provide the necessary insight for you and your team to select an injection molder that best suits your company’s needs:

  • Do they own high quality and efficient machines that work well?
  • Have they been recognized in the industry as a manufacturer of status or has the company won awards for performance?
  • Do they focus on the elimination of dysfunctional variability, such as organizational issues that can cause rework?
  • Do they offer a robust mold maintenance program?
  • Is project management software used to ensure the highest level of communication and efficiency throughout every step of the part design and development process?
  • Do your parts need to pass strict inspections or meet high safety and quality standards?
  • Is your injection molder ISO certified?

5. Product Application:

The intended use for your part or product application is critical as should be kept top of mind throughout every step of the design, development and production process. Plastics are an amazing material that can be used for many applications. While there are some circumstances that plastics cannot provide the required strength or tensile stress needed, there are many circumstances that metal parts can actually be converted to plastic to minimize weight and cost. Injection molders should consider a part’s end use to make the best recommendations in regard to design, material and production techniques.

6. Time:

Building a mold for a plastic injection molded part can range from 4-12 weeks. All representatives involved in the process should factor design revisions, part complexity, communication between designers, engineers and other individuals involved in the process, as well as account for unexpected events like shipping delays, etc. It’s always best to communicate your time constraints with an injection molder partner as early as possible to gauge their capacity and ensure you get the final production parts in hand on time.

If you’re like most product manufacturers, you have unique and specific needs. It is crucial to the success of your part that you work with an injection molder that understands your expectations and challenges. Taking these important considerations into account will help you streamline the process of choosing a plastic injection molding part manufacturer.

Are you looking for an experienced, quality-focused injection molder that specializes in low-volume production? Learn how Nicolet Plastics offers customized products and quick response in every stage of your part production.

6 Tips to Control Injection Molding Part Costs

PlasticPartBudget is one of the most important factors a manufacturer faces with getting a product to market as quickly as possible. Designing a plastic part for manufacturability involves considerations that can ultimately have a significant impact on cost. Whether you are in the initial design phase, prototyping or production, controlling injection molding costs requires analyzing of various factors. Here are a few tips to help you control plastic injection molding costs:

Collaboration:

Over the years, collaboration has taken a different form with the introduction of robust project management software. Working with a plastics manufacturer who incorporates highly effective project management software can create efficiencies within every phase of the planning and production process. With every step in injection molding building upon the next, communication and collaboration are key factors to addressing customer’s primary stress points such as timeline and budget.

Collaboration begins at the quoting state when individuals from both sides including designers, engineers and other experts will need to provide input that will help keep part budgets within or under budget.

Optimized Mold Design:

How many times have you encountered an issue in production that was the result of inadequate mold design? If the issue persists or is unresolvable with various tactics, you may have to modify or re-create the mold – both of which are expensive solutions. To avoid these costly situations, it is essential to review mold design in the early stages.

Additionally, in mold design it is beneficial to be able to produce as many parts as possible in a single shot. The ability for the plastic to eject quickly without wasting time / movements is another critical cost-savings factor.

Integrating the issues and recommendations identified in the design and simulation phases are a key aspect of effective mold design review. However, a mold’s true performance also relies on part design.

Optimize Part Design:

-Wall Thickness

Wall thickness is one of the most important factors with part design. The first rule of thumb is to determine the minimum wall thickness that will meet your design requirements. It is always good practice to work with our injection molder / design engineer to check thickness specifications for the material(s) you are considering for your part. Typical wall thickness ranges from .04 – .150 for most resins.

Important wall-thickness facts:

  • Thinner walls require easier flowing plastics
  • Longer flow lengths (distance from nozzle to the furthest corner of the part) may require thicker walls

-Undercuts

Undercuts are a feature that can add to part complexity and cost, and in some cases can even prevent part ejection. This feature is created by including holes or snaps and should be eliminated when possible. One solution would be to work with your design engineer and injection molder to include a side action, sliding shutoff or pick out.

Using sliding shutoffs, pass-through cores or by changing the parting line and draft angles may provide an easier mold build. These also reduce tooling and manufacturing costs.

-Draft

Draft is a design feature that must be added to the walls of all injection molded parts. Allocating sufficient draft not only makes it easier to remove a part from a mold, it also minimizes tool wear. Without draft, parts may stick in the mold. Having 1 degree of draft is a good starting point, however, there are considerations that may determine exactly how much draft is needed. Drafting internal features like ribs and bosses is always good practice. Remember – the more draft, the better.

While draft facilitates the removal of the part from the mold, it is particularly important in rapid injection molding to maintain parting lines, part quality and tool functionality. It typically takes working with an experienced design engineer to know how much and where to add draft.

-Gating

Each plastic part design must have a runner and ‘gate’, or a path and opening that allows the molten plastic to be injected into the cavity of the mold. Gate type, design and location can have effects on the part such as part packing, gate removal or vestige, cosmetic appearance of the part, and part dimensions & warping.

It is essential for a part designer and molder to work together to determine where the runner and gating system should be placed. To allow for the shortest overall flow length (the distance plastic flows from the gate to the outer most point of the part), gates should typically be placed at the center of a part.

If more than one gate is needed, the gates should be placed to both reduce the flow length, and must take into account the parting line created by plastic from each gate meeting. A ‘parting line’ is the line of separation on the plastic part where the two halves of the plastic injection mold meet. Ideally a part designer will account for the parting lines by designing the part in such a way that any blemish is visible on a non-cosmetic surface.

-Material Selection:

There are many resins that can be injection molded – but it is important to consider design intent and particularly what the piece needs to accomplish. For example, does the part need to be firm or pliable? Will the part be exposed to elements like extreme heat or cold? What safety factors should be considered?

The newest, most innovative materials may not be the best fit for your particular part – and may add more cost to the overall project. Working with a design engineer who is familiar to resin characteristics and behaviors when molded, will help you pick the material that best fits your needs and may save you critical time and budget in the long run.

-Mold Flow:

Working with your injection molder to perform a flow simulation is an important step in verifying part design. Flow study allows designers and engineers the opportunity to strategize gate location, runner layout, as well as optimize water placements. The level of simulation needed depends on part complexity.

-Minimize Finishes & Coatings:

Finishes and coatings include textures or patterns that leave an imprint on a molded part’s surface and are often used to reduce surface wear. Finishes, however, can add to cost with medium to high cosmetic finishes (where tooling marks are removed and the surface is textured or polished) and high quality clear finishes being the most costly.

Overall, managing the design and complexity of your part can play a huge role in the overall time and cost. If your part has many variables that need to be addressed, your design engineer and injection molding partner should provide insight regarding what can or cannot be eliminated. Time efficiencies will come with simplified designs that are optimized to fit your time, budget and product needs.

How have you overcome challenges with design and controlling part production costs?

To learn how Nicolet Plastics, Inc. can help, please contact Bob Gafvert at bob.gafvert@nicoletplastics.com.

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3 Reasons to Get Your Molder Involved in the Plastic Part Design Process

factory molding machine workshop. close up

When plastic part designers take a collaborative approach to involve mold makers early in the design process, many cost and time to market benefits are realized. Working with an injection molder who can provide expertise and recommendations throughout the design project to ensure your part is developed with the intended use, quality, budget and timeframe in mind will greatly increase the likelihood of a positive outcome.

The most successful parts are created when there is constant communication between a part designer, tool designer and manufacturer. With open consultation and communication, the team can avoid project delays and create efficiencies.

Designing a production-ready part goes beyond aesthetic and function. Here are three important considerations when optimizing a part for manufacturability:

  1. Smart Design & Material Selection

The most important first step in part design and material selection is to consider the environment in which the part will be used. This is called design intent – or the intended use of the completed part. What will the wear and tear be for the part? What temperatures will it be exposed to? Consulting with an experienced molder will help you make informed decisions about the most innovative and widely used materials to ensure your part performs at the highest level. Additionally, specialized tool designers can help you take the following design elements (among many others) into consideration:

  • Part Shape
  • Mold Design
  • Draft
  • Uniform Wall Thickness
  • Radii 
  1. Efficient Mold Design & Fabrication

A part designer and mold maker should work hand in hand to create a mold that will produce a successful part. Molding experts provide invaluable insight not only on how to produce the best part, but also how to get the mold made quickly and cost efficiently. Using design software, designers and engineers can create a mold blueprint and as part design and material selection are tested, can help with making critical adjustments.

A mold needs to be designed around a part and specific factors taken into consideration such as: Where is the gate(s) located and what is the optimal size? How will the part be ejected? Most often, computer simulation techniques such as Mold Flow Analysis are used to provide a predictive analysis and measurement to determine the success or failure of a part. Additionally, the analysis shows how the material will orient with the mold as well as expose potential warp and stress points.

  1. Benefit of Working with a Trusted Partner

Relying on an experienced molder to provide guidance and recommendations during the design and development process can save you significant time and cost for a project. Many service providers do not factor in the costs associated with material testing, radius adjustments, diameters and more. A lack of flexibility or inability to provide what is needed to produce a successful part is another roadblock that manufacturers run in to when trying to take a quick and lowest cost route.

Do your research and have a good understanding of your molder’s expertise and services provided. Working with a partner that will listen to your needs and has the expertise to make cost-saving recommendations throughout the project process, will not only save you money, but time as well.

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