In this post, we will explain to you how the injection mold cost is calculated. We are going to trace down to the hourly rate of each fabrication process, and the major variables that will affect the mold price. By reading this post, you will understand what a reasonable price for your mold should be, and whether it is possible to lower the total mold investment.
What does the injection mold cost consist of?
Making an injection mold is all about machining the raw metal blanks into components with desired precision, and putting them together to form a complete mold. Some mold components are moveable so in the manufacturing process, the plastic parts can be formed, cooled, solidified, and then get ejected from the mold.
With that being said, we can break down the mold cost like follows:
- Mold design: A proper mold design plays an important role. In order to avoid possible molding flaws, the designer needs to have experience in manufacturing similar parts, and the knowledge of versatile plastic materials. For more demanding or complicated plastic parts, a mold flow analysis will be done for the fine tune of the mold design., although the computer-aided mold flow analysis is not necessarily more powerful than human experience. A mold design fee usually ranges from one hundred to several thousand dollars
- Material: This is the most important part of total mold cost. The final mold price will usually be 3 to 5 times the material cost.
The injection mold mainly consists of several metal pieces. The material costs will be the sum of material price ($/kg) multiply their weights (kg).
The material costs should also include the electrode for EDM and accessories like eject pins, cylinders, cooling pipes and connectors.
Different mold steel varies much in price. This choice is based on production volume, the chosen plastic material, surface quality requirement, and of course, the budget limitations.
It is a bit difficult for you to calculate the material cost by yourself. You may ask 2 of your suppliers to send the cost breakdown for cross-reference, and use the mold design drawing for self-checking.
- Machining: This is usually the biggest portion of the total costs. 2 typical machining processes are CNC machining and electrical discharging (EDM). The machining cost is calculated by the hourly rate to multiply the machining time (For example, 15 hours of CNC milling x $8/hour = $120. See the table below).
- Assembly: The machined components are not ready for proper functioning in the mold yet, they need to be hand-worked, like filing, polishing, grinding, any kind of fine-tuning of dimensions and geometry for an ideal fit. The assembly process will usually take days or weeks. The assembly cost is also calculated by the hourly rate to multiply the total hours used for the assembly work. (In the below table, it is 10 hours of assembly x $8/hour = $80)
- Tax and profit: Except for the tax and other overhead fees, a reasonable profit margin should be around 15-30%. Sometimes it may be a little higher for more challenging jobs, the extra profit is for the risk (uncertainty) the mold maker is going to take. Remember the mold manufacturer is responsible for delivering the final result, which is the injection mold that can smoothly produce the plastic parts with good quality, but not merely making a mold that ends up with any sort of molding flaws.
Usual percentage of each costs
It makes sense to know what are the most common percentage of each cost, so you will know if the quotes you receive are calculated properly, and if the prices are competitive:
- The percentage of the material cost is usually between 20-35%, depending on the part size, complexity and precision level. In other words, the mold price is 3 to 5 times of the material cost. You may use this number to calculate the appropriate price range for your mold.
An example of a mold cost break down
Now, to help you better understand how the mold cost is calculated, let’s take a look at an example in the table below. Please note that we have given the hourly rate of different processes, so that you can understand how each cost is calculated.
This is a square lid for a plastic box, the basic information is as follows:
- Product material: PP
- Product dimension: 150*150*15mm
- Mold material: 718H
- Number of cavities: 1
- Ejection method: ejection plate
Our quote for this mold is $1250, the cost breakdown is listed below:
Cost breakdown for an injection mold
(We have hidden the below table for mobile devices. You need to use desktop or tablet devices to view it.)
|Catogory||Item||Description||Unit price||Qty. (unit)||Amount|
|Material||Mold base (standard)||Material 1045, outer dimension |
300*280*260mm, 60 kgs.
|Core plate||Material 718H, 280*280*80mm, 50 kgs.||$150||1 (piece)||$150|
|Cavity plate||Material 718H, 280*280*80mm, 50 kgs.||$150||1 (piece)||$150|
|EDM electrode （for core)||Copper, 150*150*20mm, 4 kgs||$35||1 (piece)||$35|
|Accessories||Bolts, hose connectores ,etc.||$50||1 (set)||$30|
|Designing||Part designing fee||$50||1 (piece)||$50|
|Mold designing fee||$100||1 (piece)||$100|
|Machining||CNC milling||$8/hour||15 (hours)||$120 |
|CNC engraving||$4/hour||10 (hours)||$40|
|Wire EDM||$1.5/hour||6 (hours)||$9|
|EDM discharging||$3/hour||10 (hours)||$30|
|Surface polishing||$8/hour||6 (hours)||$48|
|Assembly, heat treatment, |
|Mold testing||$20/time||2 (times)||$40|
|Tax, overhead and others||Tax||$90 |
Are the costs listed in the table precise?
Some costs are difficult to be predicted precisely in advance
First of all, the material cost is easy to be calculated, so the accuracy can be within 5% of the real cost.
It will be less accurate when it comes to the machining cost, it is usually a rough estimation based on the mold maker’s experience. It is hard to predict the exact machining time needed to accomplish each process (milling, EDM discharging, etc). Some CAM (computer-aided machining) software will predict the machining time but they are not precise. In order not to quote a price lower than the actual costs, the mold maker will probably quote 10~20% higher than the real cost.
However, it is also possible that they underbid the prices sometimes. It means the mold maker will have less profit on this job than he earlier expected.
The accuracy of estimation of each cost
Please look at the table below for the accuracy of each cost estimation:
|Machining||Not accurate (-5~+20%)|
|Design||Less accurate (-5~+10%)|
|Assembly, heat treatment, mold testing||Less accurate (-5~+10%)|
|Tax, overhead and others||Accurate (0~+5%)|
Overall, the profit for the mold maker will be somewhere between 15-30%, or sometimes even higher.
Ask multiple suppliers to supply the cost break down for cross reference
Before you make the final decision to place the order, it makes sense to ask 2 or 3 suppliers to submit you the cost break down for the mold, so you will know whether the costs have been calculated correctly, and which supplier appears to be more professional in the quote process.
Examples of mold costs:
Here are a few examples of our earlier jobs. If you find some parts are similar to yours, you may get a quick estimation of the mold cost.
Mold material 718H, Family mold 1+1 cavities, Polished finish. There are multiple internal and external sliders for the side holes and some internal features.
Square container, PP, 150*150*80 mm, $1,900
Mold material 718H, 1 cavity, Polished finish. We use air ejection in this mold, meaning the parts are blow out by compressed air. This way there are no ejection pin.
Mold material H13, 8 cavities. This is a very large volume product, it is critical to make each of them the exact weight. The mold is made to very high precision.
Mold material 718H, 2 cavity (2 molds). 2 molds are needed. One is for producing the substrates, the other is for TPE overmolding. High precision is required as well.
Major variables that affect the mold price
- The part size. This is easily understandable. The larger the size is, the more material and machining time is required to make the mold. An injection mold for the car bumper could weight more than 30 tons and cost nearly $1,000,000, while a small mold for a simple plastic end cap could be only $500. Making a tutorial programmed calculator would be a big investment both in time and money.
- The number of cavities. If the mold has a lot of cavities, like 16 or 24, the mold will be made a lot larger, this will certainly lead to a higher mold cost. When it is required that the part made by each cavity should be precisely identical (in weight, wall thickness, etc.), then the mold should be made to very high precision, it will drive the mold price even higher. Like this kind of mold for making dispenser caps, each mold will cost $12,000 -18,000.
- The precision of CNC machining. The hourly rate for a Sodick EDM machine or a Makino CNC milling machine is 2 or 3 times more than a non-branded machine. The time and attention given to a machining job also contribute to the final precision it will obtain (with the same machine). To give an extreme example, with very high precision machining, the mold will perfectly work when it is assembled with a very little amount of hand work, but you may not want to pay for this level of precision.
- The complexity of the part. Complex surface features or tiny details will require more machining time. Meanwhile, the undercut features will require sliders or other side action components, this will make the mold larger and more complex in structure.
- Pre-hardened mold. The pre-hardened tools are only used when the production volume is very high, or high-temperature plastics are used, like PPS, PEEK, and PES. Pre-hardened molds take more time to be machined, the cost is usually 50-100% higher than other injection molds.
- Family mold. Family molds are used to save the total mold costs for low-volume parts production, while the mold has multiple cavities for different parts. If you want the family mold to produce multiple parts in one cycle, they must be the same material and color. These parts should be similar in size and wall thickness. Even so, family molds usually have higher reject rates due to the injection process being hard to be balanced. For this reason, it is always not recommended to include too many parts in one mold.
As a matter of fact, the family mold can be used to produce each part separately, when we block some channels (gates) in production. This means each part can be made of different colors and materials, but the production cost is a lot higher, so this method is only used for prototyping or very low quantity production.
Our mold cost calculator
Is there an easy-to-use mold cost calculator?
The answer is probably no. From what you have read above, there are lots of variables in calculating the mold price, it is hard to design a program for someone with no background to do the calculation by himself (herself). To develop a tutorial programmed calculator would cost a lot of time and money…
Our mold cost calculator designed by excel spreadsheet
Calculating the mold price is like going through a simplified mold design process, it usually takes half to one hour to do the calculation for a mold.
We have designed an excel spreadsheet with a set of excel formulas to help to estimate the mold price. With the help of this spreadsheet, it will only take 1 or 2 minutes. However, the result will not be as accurate as the human calculation, but it can usually be within +/-15% of accuracy.
Our cost estimation report will look like below:
Rather than a self-help calculator, you will need us to conduct the calculation for you. If you want, please click the button on the right, and fill out the form and upload the drawing, we will get back to you shortly.
Boyan Manufacturing Solutions has experience in dealing with the most challenging jobs of plastic injection molding. If you are interested to find out more about our quality and price, please contact us today!