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:
- Part cost is strictly limited to material cost + processing cost. The calculator has been intentionally simplified so you can quickly determine a ballpark part cost. Production part costs will be affected by many other parameters including number of inserts, post decorating, post machining, special QC methods, tolerances, painting, and the actual molder. If all these additional line items were included in the calculator, it would be much too complicated and time consuming in addition to being inaccurate.
- 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 is essentially based on the hourly rate of the molding machine and the cycle time to mold each part. 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.
- The press size is determined by part weight and projected area as shown in figure 1. This cost calculator is based on projected area vs. actual surface area of the part. Therefore, all that is required is a rough estimate of the projected area.
- Injection molding presses are sized according to shot size and clamping tonnage. Tons of pressure must be applied to a mold to keep it closed as molten plastic is injected. Typically, most commodity plastics like PE, PP, Impact PS, and PVC require approximately 2.5 to 3 tons/in2. Higher performance plastics like PC, polysulfone and PBT, may require 4 to 5 tons/in2. These ranges are general guidelines. This calculator is based on 3 tons per square inch.
- Although cycle time is dependent on many factors including wall thickness, cams in the mold, molded in inserts, tool design, tolerances and material, this calculator is based on wall thickness which is the most significant variable. Cycle times can be as short as .5 sec. for bottle caps to as long as 5 mins for large, thick walled structural parts. Most parts are molded within a 30sec to 1-1/2 min cycle time, with an median range of 30 to 45 sec cycle for many parts.