The injection molding technique is essential to manufacturing because of its usefulness. The cost of injection molding cost varies from $1,000 to over $100,000, there are many factors that affect the price. (If you want to find out how to calculate the injection molding cost, please see our article: Calculating Injection Molding Costs.
In this guide, we’ll explore the key factors that contribute to injection molding costs. Furthermore, we will also provide practical tips on reducing these costs without compromising on quality. So, whether you’re a seasoned manufacturer or have just a small facility, read on to discover how to optimize your injection molding process.
What Are The Essential Factors That Affect Injection Molding Costs?
The manufacturer’s location is one of the major factors that affect the cost. If the manufacturing facility is in a place where labor is cheap and materials are inexpensive, the cost will be lower. On the other hand, if the facility is located where rental costs are high, minimum wages are high, and the facility needs to procure materials, the costs will be higher.
The manufacturer can substantially decrease the upfront cost of injection molding despite being in a location with high overhead expenses by outsourcing the production of injection molds and substrates to regions with low manufacturing prices. This is so that the initial investment is drastically reduced. Although shipping costs are incurred, they are still considerably less than the cost of producing similar goods locally.
The volume of manufacturing greatly impacts the injection molding cost. If the manufacturer has invested in an injection mold to make 100 pieces, the cost will be divided into each unit produced. If the manufacturer uses the same mold to make 10,000 pieces, they can greatly reduce the cost per unit. Similarly, bulk ordering materials for the molding process also help reduce costs.
However, there is a point at which the costs would not decline at the rate at which volume increases. At this point, the price per unit graph will taper off and the manufacturer cannot expect a price decrease even if they increase production.
Injection Mold Design
- Mold Material
The choice of mold material is a significant contributor to costs. Steel and aluminum are common materials used for injection molds. While steel is an expensive option out of the two, it is more durable and long-lasting.
Therefore, the manufacturer should always consider the expected volume of parts to produce and the desired lifespan of the mold before making this decision.
- Mold Type: Hot Runner or Cold Runner
Hot runner molds are typically more expensive than cold runner molds, but they yield a high-quality finished product with less waste. On the other hand, cold runner molds are less expensive but can result in more material waste.
- Number Of Cavities
A mold with a greater number of cavities allows production in a single cycle. Quick production results in a lower cost per unit. However, the initial cost of the mold with more cavities is high because of its complexity.
- Mold Surface
The surface finish of an injection mold can also impact the overall cost. A mold with a smooth surface finish is expensive but yields a higher-quality finished product. On the other hand, it is inexpensive to get a rough finish, but it may result in a lower-quality finished product. The choice of mold surface should be based on the desired outcome and the budget available.
Plastic Part Design
- Part Size
Manufacturing molds for larger parts require more material which increases the initial costs. A larger part also requires more injection molding material. Additionally, to manufacture larger parts the manufacturer will have to get larger and more complex molds developed, which are relatively expensive.
- Parts Structure
Parts with complex shapes or multiple cosmetic features may require advanced molds. It increases the overall cost of production. On the other hand, simple structures are also easier and faster to manufacture, resulting in a lower overall cost.
- Design Tolerance
Tighter tolerances require more precise manufacturing and a higher level of quality control. On the other hand, looser tolerances might lower the price, but yield a finished product that has low quality. Click here to decide your injection molding part tolerance.
- Secondary Finish
Secondary finishing processes such as galvanizing, logo printing, or laser engraving require additional equipment, tooling, or injection molding steps. It adds to the time to manufacture, therefore impacting costs through higher overhead and labor costs.
- Part Assembly
Even though developing the mold is a one-time cost, the higher time required for assembling multiple plastic parts into a finished product increases labor and overhead costs.
How to Reduce Injection Molding Cost?
The cost of manufacturing processes has a huge impact on the price competitiveness of the product. A high-end screwdriver set that costs $100 and has intricate engravings and a polished finish won’t do well on the market if the majority of screwdrivers cost an average of $50. People are more likely to purchase the less expensive choice even though the $100 set has more features and a better design.
Besides, the demand for the more costly $100 product gets even lower if a different manufacturer uses cost optimization techniques to produce a screwdriver set of comparable quality and sells it for $50. This is because customers would be less inclined to spend more on elaborate engravings and finish if the same quality could be obtained for less money.
Here are 8 tips that will help you reduce the cost of injection molding without compromising on the quality of the finished product:
1. Assess the Structural Requirements
A Design for Manufacturability (DFM) analysis can help you assess what part size you should go for, the surface finish required, and the design tolerance. Through the DFM, the manufacturer can also simplify the design, reducing the number of components and the number of manufacturing steps required.
2. Design for Efficiency
In an ideal world, it would be possible to get a high-quality finish with a laser-engraved logo without any impact on costs. However, if the manufacturer wants injection molding on a budget, it is necessary to simplify the design and let go of cosmetic features that add to the cost.
3. Lean Design
The lean design approach helps minimize the material used in manufacturing without compromising its structural integrity or performance. Solid part areas that are now hollow require more material and more cooling time. When the manufacturer implements a lean approach, they could also consider reducing the size of the molded part. Additionally, lean design means avoiding thick molds, and the part strength is maintained through ribbing, gussets, and other internal structures that distribute stress.
4. Select the Right Material
If your part is the rubber on a toothbrush, there’s no need to source expensive material for the job. On the other hand, the manufacturer will have to select the material accordingly for a handle that needs durability and grip. Therefore, it is crucial to choose a material that suits the needs of the part being manufactured.
5. Crafty & Intelligent Mold Designs
It is critical to develop intelligent molds that help minimize material use. Here are some tips for developing crafty molds:
- Manufacturers can use hot runner systems to maintain a consistent temperature throughout the mold. It helps reduce the amount of scrap produced.
- Interchangeable inserts can help significantly reduce the cost of production. It is because a single mold can be used for multiple-part designs. However, it does increase the time to manufacture.
6. Mold Modification – Master Unit Die (MUD)
A Master Unit Die (MUD) is a tooling method that uses a pre-manufactured or standardized mold base. The custom inserts go into the standard base, then the tool is put through the injection molder. This approach helps reduce lead times and tooling costs.
The manufacturer can use a standardized mold to reduce costs rather than opting for a specifically designed one. Also, through MUD manufacturers can quickly and easily modify the mold to accommodate changes in production requirements. So, there’s no need to invest in new molds for manufacturing batches with slight differences.
7. Family or Multi-cavity Mold
Multi-cavity molds might be expensive to manufacture, but they allow production in a single cycle. You can lower your cost per part by producing a higher volume of parts. You can also create a mold that fits multiple parts together, so long as they are all relatively similar in size and material. If you think about it, the more parts you can get out of your mold at one time, the faster your production speed and the fewer cycles the mold would need to go through. That’s maximizing efficiency.
So, by investing in a complex multi-cavity mold initially, manufacturers can produce a huge volume of parts quickly. Thus, it reduces the time to manufacture which impacts overhead and labor costs.
Cavity tools for injection moulding
8. Avoid Excessive Feature Cosmetics
At times additional processes or unnecessary cosmetics on features increase the cost considerably. If there’s a budget to stick to, manufacturers should only choose processes that are needed. For example, the manufacturer could reduce secondary finish processes like galvanizing, logo printing, or laser engraving.
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