How to Use the Calculator

This cost calculator is provided to assist you in estimating part cost for injection molded parts. The estimated total cost can be used for budgetary purposes during your project planning. You should be aware that these are only estimates and that actual part costs can only be obtained by submitting final CAD files and production control drawings to a molder.

The part cost estimator is based on the following parameters:

    • This calculator is strictly limited to:
      material cost + processing cost.
    • The calculator has been intentionally simplified so you can quickly determine a ballpark part cost. Actual production part costs will be affected by many other parameters including:
      • Number of insets
      • Post decorating
      • Post-machining
      • Special QC specifications
      • Tolerances
      • Painting
      • Your molder

If all these additional line items were included in the calculator, it would be too complicated, time-consuming, and inaccurate.

Material Cost

  • A limited list of common resins has been included in our pulldown menu. If your resin is not listed, you can enter the material density manually.
  • Since material prices are extremely volatile, dependent on order size, color and specific grade, it’s impossible for us to provide you with an accurate cost per pound. You must therefore manually enter the material cost per pound.

Processing Cost

  • Processing cost is essentially based on the hourly rate of the molding machine and the cycle time to mold each part. Hourly rates for larger presses are generally more expensive than smaller ones. There are many other manufacturing parameters that will affect the final molded part cost as previously stated, but the basic molding cost per part can be estimated based on the hourly rate divided by the number of parts molded per hour.
  • Injection molding presses are sized according to shot size and clamping tonnage. This calculator is based on 3 tons/in2 of the projected area of the part. which is a good average. Actual clamping force may vary between 2 to 5 tons/in2 based on material, wall thickness, and shot weight.

 

The projected area is determined based on a shadow of the part vs.the actual surface area of the part as shown in figure 1. Therefore, all that is required is a rough estimate of the projected area as shown.

    • Estimating Cycle Time: Cycle time is dependent on many factors including wall thickness, cams in the mold, molded in inserts, tool design, tolerances and material. Cycle times can range from 1/2 sec. for bottle caps to as long as 5 mins for large, thick-walled structural parts. Most parts are molded within a 20 sec to 60 sec cycle time. You can play with different cycle times to see how it will affect your part cost or start with a 45 sec. cycle time to begin your estimate.