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How much does injection molding cost? How to avoid high cost?

How much does injection molding cost?

A small and simple single cavity plastic injection mold typically costs between $1,000 and $1,000. Very large or complex molds can cost as much as $100,000 or more. On average, a typical mold that produces a relatively simple part small enough to hold in your hand costs about $20,000.
Don’t forget that the price of the mold is just the beginning. To determine the overall plastic injection molding cost for any project, you must also consider the cost of raw materials, operations, and repairs going on.

Is injection molding expensive?

The start-up cost of running a machine at scale can be expensive, but as you continue production, the price of the project will get better and better. If you’re looking at unit price, plastic injection molding is one of the cheapest and most cost-effective forms of manufacturing. With injection molding, the more units you create with the mold, the cheaper the price per unit.
Injection molding is one of the main processes for making plastics. It is widely used for mass production of identical parts with tight tolerances. This is a cost-effective and extremely repeatable technique for producing high-quality parts for high-volume production. 
This is a fast, intensive process that involves high temperature and pressure to inject molten material into the mold. The molten material depends on the scope of the manufacturing project. The most popular materials are various thermoplastics such as ABS, PS, PE, PC, PP or TPU, but metals and ceramics can also be injection molded. The mold consists of a cavity that holds the injected molten material and is designed to closely mirror the final characteristics of the part. 
Typically, the primary cost driver for injection molding is tooling cost, also known as tooling cost. The cost of designing and manufacturing a mold depends on the throughput required, the complexity of the part design, the mold material, and the process used to make the mold. 
Simple low-volume 3D-printed molds can cost as little as $200, while designing and manufacturing complex molds for high-volume production can cost the $200,000 mark. Despite the considerable fixed start-up costs, the variable cost of the injection molding process is lower due to the low price of thermoplastic materials, short cycle times, and tapering labor requirements due to automation and economies of scale. This means that the variable cost of production is low, the process becomes more efficient, and the cost per part decreases as production increases as costs are distributed among hundreds or thousands of parts.

What are the costs of injection molding

Injection material cost

Material selection is another consideration in determining the cost of plastic injection molds. For example, any plastic product made of fiberglass filled material will wear out the most common molds. Only molds made of hardened tool steel can withstand injection molding of fiberglass-filled materials.
Various plastics can be used for injection molding, including ABS, PS, PE, PC, PP or TPU, depending on the requirements of the final part.
The cost of purchasing mold material varies depending on the material selected. Thermoplastic pellets cost about $1 to $5 per kilogram. 
Material cost is determined by the design of the model, the material selected, and the amount of material used to perform the injection molding process.

labor or service costs

Equipment associated with injection molding is often self-regulating and relies on automation to get the job done. CNC machines, EDM machines, and 3D printers rely on CAD-designed specifications to produce molds. Injection molding machines also rely on automation to inject material into molds, and industrial IM machines often cool and eject finished products automatically.

Labor costs include:

Setup/Configuration Costs: Setup labor focuses on the time it takes to configure the equipment used to produce molds and finished products. 
Repair Costs: Repair and maintenance tasks involve replacing defective parts and using tools to perform maintenance procedures. 
Monitoring costs: Despite relying on automation, equipment operators still need to monitor the progress of the injection molding process. Operator wages incurred during this process are added to the total cost of injection molding. 
When produced in-house, these costs are included in labor costs. When a business outsources injection molding, labor and markups from the service provider are added to the cost of the service.

Process used

Injection molds are generally made in three ways:

CNC Machining: CNC machine tools are the most commonly used tools for making high-precision aluminum and stainless steel molds. CNC machining removes material by rotating tools and stationary parts. Machining can produce molds with very complex cavity designs, but they can require multiple tool changes, which slows down the process and means that costs increase with complexity. CNC machines are industrial tools that require skilled labor and dedicated space, which means many companies outsource mold production to service providers.
Electrical Discharge Machining (EDM): EDM methods are often used to create highly complex mold designs that cannot be easily replicated using standard machining methods. EDM involves the use of workpiece and tool electrodes to create the desired mold shape. The tool electrode and workpiece electrode are separated by a dielectric fluid and are subjected to voltages that cause repetitive current discharges. The discharge is responsible for shaping the workpiece electrode into the final mold. EDM is very accurate and usually does not require any additional post-processing. Similar to CNC machining, EDM is an industrial process that many companies outsource to machining shops.
3D Printing: 3D printing is a powerful solution for making injection molds quickly and cost-effectively. It requires very limited equipment while saving CNC time and skilled operators for other high-value tasks. Manufacturers can benefit from the speed and flexibility of in-house 3D printing to create molds that can be used on desktop and industrial molding machines. Additionally, product development benefits from the ability to iteratively design and test end-use materials before investing in hard molds for mass production. Stereolithography (SLA) 3D printing technology is an excellent choice for injection molding. It is characterized by a high surface finish, high accuracy of mold transfer to the final part, and easy demolding. The 3D prints produced by stereolithography are chemically bonded, making them fully dense and isotropic.

Molded part cost

Material selection and part weight

The plastic material you choose for a plastic part is not only critical to the function of the part, but also plays a huge role in the cost of its manufacture. The cost of plastic raw materials can range from $1 per pound to $25 per pound. Therefore, attention should be paid to reducing the weight of the part as much as possible in the design of plastic parts.
Selecting the right type of plastic can also help speed up the cycle time or productivity of the part, thereby reducing overall costs. For small parts, material cost has little impact on unit price, while productivity has a big impact. On larger, heavier parts, material cost has a big impact on unit price and productivity.
$ Material Part Cost = $ Plastic Material Price x Part Weight lbs

Cycle Time and Mold Cavities

“Cycle Time” is a term used in our industry for injection molding and CNC machining. Simply put, it is the time it takes for a machine to complete a production cycle. The entire injection molding cycle time consists of the following steps:

  1. Clamping time
  2. Injection filling time
  3. Injection package/holding time
  4. Cooldown time
  5. Mold opening time
  6. Part ejection or removal time
  7. Recycle time (only if the part must be run in semi-automatic mode by the machine operator)

11 injection molding design considerations to help you reduce manufacturing costs:

  1. Eliminate undercuts
  2. Remove unnecessary features
  3. Using the core cavity method
  4. Reduced appearance finish and appearance
  5. Design Self-Material Parts
  6. Modify and reuse molds
  7. Pay attention to DFM analysis
  8. Use multi-cavity or family molds
  9. Select the on-demand production option
  10. Consider part size
  11. Use overmolding

While injection molding may seem costly compared to processes such as CNC machining and 3D printing, its scale and ability to manufacture thousands of parts make it a cost-effective solution for mass production. Determining injection molding cost is a combination of several factors. The main determinant of molding cost is the time it takes to produce the mold. This means that the more complex the geometry of the part, the more expensive it is to manufacture. Simple parts without undercuts or more advanced finishes will be the most affordable.
In addition to unit cost, consider materials. Many plastics overlap in strength and function, but some are inherently easier to mold, reducing part cost. When you upload your design to elimold, you can experiment with different materials in the interactive quotes you receive.

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