The importance of knowing the injection mold cost
If you are planning to outsource a plastic injection molding project, you may wonder how to find a fair price for the injection mold. 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. Our online calculator will let you understand what a reasonable price for your mold should be, and whether it is possible to lower the mold investment.
List of content
Empirical quotation method
The basic structure of injection molds
The composition of mold cost
The material cost
Design fee
Machining cost
Assembly fee
Tax and profit
Usual percentage of each costs
The accuracy of estimation of each cost
Material cost multiplier quotation method
What determines the price factor
An example of mold cost breakdown
How to use our online mold price calculator
Mold cost calculator
Examples for verifying the calculatorrs accuracy
Empirical quotation method
There are many components in a mold, and they have to go through a lot of different machining processes, so its costing is complicated. The calculation of material cost is relatively simple and accurate, but the processing cost is not. Because the processing cost is determined by the selected processing equipment and its processing time, and the processing time is very difficult to be predicted accurately, either by human estimation or by using 3D simulation software.
That’s why mold quotes are usually based on estimates.
To quote a mold, you need to design the mold structure first, then compute the material cost, estimate the machining cost and other costs, and finally come up with a quote for the mold.
Of course, this estimate is not arbitrary or rough, because:
- The estimation of material cost is relatively accurate;
- The machining cost estimate is based on mold dimensions and previous experience with similar products;
- The mold maker understands that if he overbid, he may lose this opportunity.
There is still some room for ambiguity here, which we will discuss further next.
The basic structure of injection molds
An injection mold is made up of a bunch of steel pieces. Each piece is machined to the desired shape and tolerance, then they will be assembled together into a complete injection mold where the molten plastic will be injected into, formed, cooled, solidified and ejected from the mold.
Some injection molds are more complex than others, which have elaborate structures and many moving parts, but their basic structure are similar.
In principle, the injection mold consists of the following components:
The mold components can be classified into 2 groups:
- Main components: Cavity plate, Core plate, Slider, Spacer block, Clamp plate (top and bottom), Ejector plate (top and bottom).
- Accessories: These include sliding pillar, ejector pins, sprue bushing, locating ring, springs, some molds will have hot runners, and so forth.
Here are some explanations:
An enclosed chamber is formed by the Core Plate, Cavity Plate and Slider when the mold closes. This is where the plastic part takes shape and hardens. The mold opens and these components separate to let the hardened plastic part out.
Many plastic parts have undercut designs, so the sliding mechanism is common in injection molds. There are two main types of sliding designs. One uses inclined rails to convert vertical motion into horizontal motion. The other use hydraulic or pneumatic cylinders.
The ejector pins, the top and bottom ejector plates make up the ejecting mechanism. This mechanism is vital for smoothly removing the parts from the mold after they are formed.
The ejector plates push the ejector pins up, which in turn pushes the cooled plastic part out.
The composition of mold cost
With that being said, we can break down the mold cost like follows:
1. The material cost
The cost calculation of the injection mold starts from the material cost. First, we will calculate the costs of the main steel plates.
The classification of material costs
- The main plates: Core Plate, Cavity plate, slider, clamping plate, spacer blocks, top ejector plate, and bottom ejector plate;
- Slide components: Slider, lifter, cylinders or other sliding mechanisms;
- Accessories: sliding pillars, ejector pins, hot runners (optional), springs, fasteners, etc.
- Auxiliary material: bronze or graphite used as the electrode for EDM.
An example of how to calculate the Cavity Plate
Based on the size of the plastic parts, the number of cavities, and the basic structure (whether there are sliders, cores, two-plate molds or three-plate molds, etc.), we can calculate the size and weight of the steel plates and then get the cost of them.
When the product size is L*W, and there are 2 cavities, then the distance between cavities R, and the distance from cavities to edges T1, T2 can be obtained from empirical formulas, so we can get the length and the width of the cavity plate Lca and Wca,
- Lca=2W+2T1+R
- Wca=L+2T2
And the height Hca is also calculated by an empirical formula.
When calculating the raw material dimensions, some allowance needs to be added to the length, width, and height. Then we have the material weight of the Cavity Plate.
Weight of raw material=Length x width x height x 7.85 / 1,000,000 (kg)
(Note: the units are mm, kg in this formula.)
Likewise, we will do the same calculation for the other steel plates and sliding components to get their weight and costs, and add them together.
2. The design fee
A successful plastic molding project starts from a good mold design, which requires a lot of skill and experience and often involves teamwork. Designers, mold makers, and others collaborate and combine their input to find the best option.
Depending on the size and complexity of the mold, the design fee usually ranges from $100 to $300, sometimes could be even higher.
A skillful designer’s hourly rate can be 30 to 40 dollars, this sounds a bit high, but they can finish the design of 8-10 simple injection molds in a day (12 hours), so their charge is reasonable for their output.
3. The machining cost
Machining is the most expensive part of the mold. The cost also depends on the type and grade of the machining equipment. The hourly rate of top brand equipment is 2-3 times higher than that of ordinary equipment.
The formula for calculating machining costs is:
Machining fee = hourly rate X machining time
Since it is hard to estimate the machining time accurately, we can only make an approximation based on the size of the plastic part and the actual processing cost of similar parts in the past.
4. The assembly fee
The mold assembly is time-consuming work. It includes adjusting the dimensions that are not in place during machining, making all the moving parts fit with appropriate tightness, and debugging the issues that were not anticipated in the design stage. The more complex or the more expensive the mold is, the longer it takes to match the mold. For example, a 10,000-dollar worth of mold may take 50-100 hours to match.
However, the time required for mold assembly cannot be precisely estimated either.
5. Tax and profit
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 excessive molding defects.
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:
| Item | Percentage | |
|---|---|---|
| 1 | Material | 20-35% |
| 2 | Machining | 25-40% |
| 3 | Assembly | 15-20% |
| 4 | Mold design | 5-10% |
| 5 | Tax, profit | 20-30% |
The accuracy of estimation of each cost
Some costs are difficult to be predicted precisely in advance
As mentioned above, some costs, especially machining and assembly fees, cannot be precisely estimated when calculating quotations. Only the fuzzy quotation method can be used. The so-called fuzzy quotation is that it will be the quotation actually slightly upward than the actual cost, but there is also the possibility of downward fluctuation. And the upward and downward fluctuations between different costs may offset each other, to achieve the overall fluctuation is not very large.
| Item | Material | Machining | Design | Assembly, | Tax, Profit |
| Accuracy | (0~+5%) | (-5~+20%) | (-5~+10%) | (-5~+10%) | (0~+5%) |
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.
Material cost multiplier quotation method
In the above quotation methods, each cost is estimated separately. But in actual operation, mold factories often use simpler methods, that is to calculate material costs first and multiply by a price factor according to the mold size, complexity of the mold and so forth.
Mold price=Total material cost * price factor
This price factor for a typical injection mold is between 2.5 and 5.
What determines the price factor
The mold size: The larger the mold, the lower the price factor. For small molds, the material cost is low, but some other costs do not drop so low correspondingly. While for larger molds, the other costs do not increase in proportion to the material cost increase.
Complexity: The more complex the mold is, the higher the price factor is. Molds with simple geometry can be machined with a large milling tool and require a relatively short time. But complex shape molds need to be machined with small milling tools for some fine details, some need to be machined with EDM, and the machining time is much longer. Also, complex molds have more sliding mechanisms and need more parts to be composed.
Precision: The higher the accuracy of the mold, the higher the price factor. Because this will be machined with more expensive equipment, and the mold structure will be adjusted accordingly.
The number of cavities: For molds with more number of cavities, hot runners will be used to solve the problem of even distribution of pressure/flow per gate, the dimensional consistency of each cavity is required to be higher, and the mold maker will also take higher risks. These are the factors that will drive the prices up.
Like this kind of injection mold shown in the right picture for making dispenser caps, each mold will cost $12,000 -18,000.
The hardness of tool steel: The harder the mold steel, the higher the price factor. This is because harder mold steels make the milling time longer, the even harder mold steels can only be machined with EDM.
Tip: 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.
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. | $100 | 1 (piece) | $100 |
| 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 | Assembly | $8/hour | 10 (hours) | $80 | |
| Heat treatment | $0.5/kg | None | |||
| Mold testing | $20/time | 2 (times) | $40 | ||
| Tax, overhead and others | Tax | $90 | |||
| Administration fee | $95 | ||||
| Profit | $100 | ||||
| Total | $1,267 | ||||
So in this particular case, the general composition of the mold cost is:
How to use our online mold cost calculator
This online injection mold cost calculator uses the part dimensions, the number of cavities, and the number of slides to calculate the mold dimensions and then estimate the mold price. It is not 100% accurate but can provide a close enough estimation.
Here is the explanation of how to use this mold cost calculator. First, you need to enter the values of the following:
Make sure the length (L) is bigger than the width (W), otherwise, their values will switch automatically.
Note: Maximum value for L, W and H: 600mm
Minimum value for L, W and H: 8mm (please use 8mm if the value is smaller)
There are 3 options: 1 cavity, 2 cavities, and 4 cavities.
There are 3 options here: no slider, 1 side of sliders and 2 sides of sliders
Note: If there are multiple sliders on the same side, they are considered 1 side of sliders.
For helical gears, please choose 2 sides of sliders because there is a helical ejecting mechanism.
Where P20 – low end; 718H (medium); H13 (high end), these mold steels are the most commonly used.
C45 is also sometimes used in low-end applications.
There five categories: very simple, simple, medium, complex and very complex.
Simple means fewer small details, low precision, smaller and fewer sliders, and shallower ribs, while complex means the opposite.
You need to choose 2 or 3 complexity levels so the output will cover a price range for better reference.
Here are the outputs of the calculation:
This is the estimation of the mold dimension so you will have a visual conception of how the mold will look like.
Since the steel for the Core and Cavity are made of more expensive steel, they are often embedded into the A/B plates so they can be made smaller.
The calculator will automatically compare the results of embedded and single-piece designs and choose the better option.
This calculator will give 2-3 prices, each corresponding to a different complexity level, so that you can get a price range that provides a better reference. Each price provides a cost breakdown and their percentage.
These are the results obtained from the simulation calculator. If you would like a more accurate and realistic manual quote, please contact us
Examples for verifying the calculator's accuracy
Here are some examples of mold prices to verify the accuracy of the mold price calculator. It can be seen that for plastic products with general complexity and accuracy, its valuation is still close.
| Part dimensions | Number of cavities | Number of slides | Steel for Core and Cavities | Complexity, |
| 350*135*40 | 1*1 | 1 | H13 | Medium |
| Additional mold information | Calculator Price | Real Price |
| Hot runner, 3 sub-gates | $8450 | $8900 |
Item name: Storage box with mesh.
Material: PP
| Part dimensions | Number of cavities | Number of slides | Steel for Core and Cavities | Complexity, |
| 150*150*80 | 1*1 | 0 | P20 | Very Simple |
| Additional mold information | Calculator Price | Real Price |
| Cold runner. Ejector plate with air nozzle | $2170 | $2350 |
Item name: Plastic case for power socket.
Material: ABS
| Part dimensions | Number of cavities | Number of slides | Steel for Core and Cavities | Complexity, |
| 80*40*40 | 1+1 family | 1 | 718H | Very Simple |
| Additional mold information | Calculator Price | Real Price |
| Cold runner, edge gates | $2290 | $1960 |
Item name: Plastic enclosure of drive device.
Material: PC
| Part dimensions | Number of cavities | Number of slides | Steel for Core and Cavities | Complexity, |
| 243*105*38 | 2 | 0 | 718H | Simple |
| Additional mold information | Calculator Price | Real Price |
| Cold runner, edge gates | $4965 | $4690 |
However, for some plastic parts with special requirements, the price calculated by this calculator will be low, such as this LED lamp lens, which will give a much lower price than the actual price. This is because the lens has high requirements for the projected light pattern, and its geometric shape accuracy is very high.
Item name: LED lens.
Material: PC
| Part dimensions | Number of cavities | Number of slides | Steel for Core and Cavities | Complexity, |
| Dia. 50*8 | 1+1 family | 2 | S136 | Very Complex |
| Additional mold information | Calculator Price | Real Price |
| Cold runner, edge gates | $5795 | $11000 |