Plastic Injection Molding Pricing Factors 

Several factors come into play when quoting a plastic injection molded part. Some of these factors are listed below along with a comment that should help you hone in on the most efficient price possible.  Refer to the Bruin Plastic Design Workshop section for detailed explanations and illustrations.

Material Selection for Plastic Injection Molding

Always research the material properties and choose the most basic material possible that can achieve the form, fit and function you are needing. Materials such as polypropylene, polyethylene, polystyrene, polycarbonate, ABS, acetal, and nylon are just a few common base materials. Most of these materials can be formulated to include fillers to enhance the properties.  Although Bruin is fully capable of molding these filled materials, only choose these grades if necessary.  The more you stray from the basic material, the more you will pay.  Also, stick with natural color or black if possible.  Most materials are commonly available in both.  Custom colors = cost!

Plastic Injection Molding Tolerances

Keep tolerances as wide as possible. The wider the tolerance, the less expensive the part.  You should ask yourself the question “what do I need?” rather than ask the molder “what can you hold”.  As the part gets larger, the tolerance needs to get wider to achieve the capability.  A rule of thumb is to increase the tolerance .001” to .002” per inch increase in feature size.  Bruin follows the Handbook of the Society of the Plastics industry Standards for Molding Tolerances and will only warrant parts that strictly follow this standard.

Injection Molding Part Design

When designing a plastic part, build the plastic around the function of the part. Start with the function and mating parts and add a consistent wall section around it.  If areas need to be strengthened, add ribs and gussets with a thickness of no more than 60% of the adjoining wall it intersects with.  This will help keep the amount of plastic to perform the desired function at a minimum.  This saves money in raw material cost as well as cure time which are the two main drivers in the cost of a molded part.  Bruin has a fully staffed engineering department ready to assist you in proper part design.

Plastic Injection Molding Quantity

In general, plastic injection molding is geared more for high volume production.  Quantities are typically in the thousands, tens of thousands, hundreds of thousands or millions per year.  Tooling costs can be expensive and can be a little less painful when amortizing the cost over many parts.  Here at Bruin, we emphasize taking advantage of long continuous runs.  When the mold is initially set up to run production, it takes a certain amount of time for the conditions to level off and begin producing consistent parts.  Once it reaches that level of equilibrium, the cost of the setup starts to diminish and the Bruin lights out, automatic molding advantage takes over.  The longer the run, the more the human labor costs become negligible.

Simple or complex, Bruin Manufacturing provides the fastest and most affordable plastic injection molding services for any application. Combining knowledgeable engineering personnel with highly trained technicians and advanced custom manufacturing processes, we can design and manufacture premium plastic parts with precision, speed, and quality.

Contact us for more information about pricing factors for plastic injection molding.

FAMILY OWNED PLASTIC INJECTION MOLDING COMPANY

Headquartered in Marshalltown, IA since 1949

At Bruin Manufacturing, we are the small parts problem solvers. We offer total, integrated custom injection molding services that can meet your needs for quality, time, and price.

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