Full_Assembly_Bowls.jpgWhen purchasing injection molding tooling and services, buyers need to establish a mechanism to analyze the quoting process and assess the supplier’s ability to meet the project requirements.    Project requirements vary greatly when purchasing injection molded plastic parts based on the quantity, material, complexity of the part and end use.   Ensuring the injection molder understands the complete scope of your project is vital, because it affects all the downstream processes for providing an accurate quote.   Starting with the tool design, building the tool, validating the molding process and thru to production.

Here are a few guidelines to help you through the quoting analysis process.   

Understand the Scope of the Project

First, providing 2d part drawings or 3d cad models to the injection molder is necessary.  The part drawings and cad models specify the details on the size and complexity of the part oppose to just words, which can be interpreted differently and information can be missed.   Missed details create significant differences in mold design, cost and final outcome.   

Because critical dimensions and total dimensions determine validation costs and requirements, the more critical dimensions the more costly.   Reducing the number of critical and total drawing dimensions and focus on what is the critical function of your part or device, and make sure your drawings reflect that information.     

Reducing the number of critical dimensions and total drawing dimensions and focusing on what is the critical function of your part or device, and make sure your drawings reflect that.   These critical dimensions and total dimensions determine validation costs and requirements, the more critical dimensions and total dimensions the more costly.

It is important for your injection molder for quoting purposes and production to understand the end application and usage conditions of your product.  Variables such as temperature, chemical contact, applied stresses during use, water absorption, lubricity, wear resistance as well as color and aesthetics, govern if the resin is suitable for the application.

End application information is significant for the plastic injection mold design and fabrication stage. The resin chosen for the product effects if the resin can be manufactured with the part design details given and what type of material the mold will need manufactured from to provide the requirements of the end product.  It is typically not practical to change resins after the mold is manufactured.

Another element to make sure you receive an accurate quote for your project is providing the part volume and the expected lifespan of the product.   The part quantity determines the type of injection mold that must be fabricated to manufacture the part.    The lifespan of the product also determines what type of tool needs to be fabricated to sustain the annual volume for a certain amount of years.   

Will your project require any assembly and packaging requirements?   If yes, this can be incorporated in to the quote for the overall project cost, since many injection molders provide these types of services to help manage and complete your project.   

Another critical aspect of your project is the quality requirements and validations your project requires. Ensuring the injection molder has the proper registrations or certifications your project requires and will provide the proper documentation and evaluation for your project.     This will let your injection molder know from the start if other validations besides FAIRs and initial mold samplings need to be performed.  

Ungoing Costs of Injection Molding

The injection mold appears to be the most costly expense of your project because it is the upfront visible expense.   Size and complexity of the part to be molded and the number of cavities of the injection mold are major influences on the initial price of the tool.    Commercial injection mold bases come in standard sizes.  Typically, a mold builder purchases a standard mold base and then further machines to meet the requirements of a specific project.   The part geometry is machined either directly into the mold or into inserts specific only to that mold.  In addition to the part, runner and gate geometry, all the mechanical elements of the mold need to be designed, machined and installed for each new mold.  

Raw material is a major ongoing cost of the injection molded part, which affects long-term costs.   There are vast resins to choose from for your product, but most resins fall into two categories:  commodity resins or engineering resins.   Commodity resins are usually lower in cost and widely available.   Engineering resins have superior properties over commodity resins but the cost varies greatly depending on the physical properties of the resin. 

The most important thing is most projects never go exactly as planned, but reviewing these guidelines will ensure you select the injection molder that will run your project smoothly and minimize the risk of costly problems and failure.

Crescent Industries is an injection molding partner that will design, build your injection mold and run production.  Crescent will optimize the manufacturing process and offer tooling solutions to achieve your project and production requirements. 

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Topics: custom injection molding