This method will give a budgetary part cost estimate but is not a substitute for obtaining actual molder’s bids.

1. Determine the Part Weight. Weight the part on an accurate scale. Most molders use a gram scale. The part weight should be accurate to the nearest 1/100 of a pound. The conversion ratio from grams to pounds is: Grams X .0022 = Lb.

2. Determine the Resin Cost per Part:. Most molders make their cost estimates based upon one production run and resin shipment per month. Now that you know the part weight, you can determine the usage of resin per month. Contact the resin manufacturer to determine the cost per LB of the resin that your part is using. See our Links page for a direct link to the Resin Manufacturers. The resin manufacturer sells the resin with price breaks based upon quantity. Ask the resin manufacturer for the resin price based upon your parts usage per month. Resin cost per part is: Resin Cost per LB X Part Weight Each = Resin Cost per Part.

3. Determine the Cycle Speed: Although cycle speeds can vary based upon resin, dimensional requirements and the tooling design, the following table will provide a estimate that will provide a relatively close estimate. Wall thickness is measured at the thickest point.

Wall Thickness	Cycles per Hour
.040"	250
.060"	180
.080"	140
.100"	100
.120"	80
.140"	60
.160"	50
.180"	40
.200"	30

Determine the Parts Produced Per Hour by multiplying the number of cavities (or sets if a family mold) times the cycles per hour: Number of Cavities X Cycles Per Hour = Parts Produced Per Hour. This formula is also handy to determine production capacities.

Machine Rate The machine rate varies widely from area to area and by industry and part quality requirements. The following is a range that may be used for estimating purposes. Some molders Hourly Rates may exceed either below or above the range shown.

Machine Size in Tons	Hourly Rate Range
20-50 tons	$30-$70
50-150 tons	$35-$75
150-300 tons	$40-$85
300-500 tons	$45-$90
500-750 tons	$60-$120
750-1000 tons	$70-$140
1000-1500 tons	$90-$200

Machine Labor Cost Per Part Take the hourly rate and divide by the parts per hour. Hourly Rate / Parts per Hour = Machine Labor Cost Per Part.

Cost Per Part Estimate: Add Resin Cost Per Part with Machine Labor Cost Per Part. Resin Cost Per Part + Machine Labor Cost Per Part = Cost Per Part Estimate.

Example:

Assumptions

Part Weight::1/4 or .25 lb.

Resin Cost Per lb.: $1.00

Wall Thickness: .100"

Cycle Per Hour: 100

Cavities: 2

Machine Rate Hr: $50.00

Step 1: Resin Cost Per lb. X Part Weight Each is ($1.00 X .25lb.) = $.25 Resin Cost Per Part.

Step 2: Cycle Per Hour X No. Cavities is (100X2) = 200 Parts Produced Per Hour

Step 3: Machine Rate Per Hour / Parts Produced Per Hour is ($50.00 / 200)= $.25 Machine Labor Cost Per Part

Step 4: Resin Cost Per Part + Machine Labor Cost Per Part ($,25 + $.25) = $.50 Cost Per Part Estimate.