Injection moulding is a popular manufacturing process used for producing a wide range of plastic components, and one variation of this process is family injection tooling.
This method involves creating a variety of different parts within the same tool. While family injection Tooling has distinct advantages, it also has some limitations. In this blog, we'll dive into the pros and cons of family injection tooling to help high light when it might be the right choice for your production needs.
What is a Family Injection Tooling tool?
Family injection moulding, or family tooling, refers to the process of designing a tool that can produce multiple different parts or cavities in one shot or cycle. These parts may have varying sizes, shapes, or functionalities, but they are all made from the same material and are injected in a single shot of plastic. For example, a family tool may produce a complete set of plastic components for a product where the parts are different, but each part can be tooled simultaneously using the same base material and are ejected as a set ready for assembly.
This type of tooling can be an attractive option for companies looking to reduce tooling and production costs, especially in small to medium-sized sized businesses (especially start-ups) with tighter budgets operating on the ‘smell of an oily rag’ and who tend to have lower production run volumes.
However, family Tools also introduce certain challenges that need to be carefully considered before adopting this method.
Pros of Family Injection Tooling
Cost Savings on Tooling
One of the primary benefits of family tools is that they reduce tooling costs. In traditional injection tooling, each part requires its own dedicated tool, which can be expensive to design and manufacture. This comes largely down to the cost of tool steel per kg. There are a variety of tool steel qualities in a ranges of prices per kg, but a kg is a kg regardless of the price. More tools, means more steel.
In contrast, a family tool produces multiple parts in one tool, which consolidates the tool-making costs. For manufacturers looking to produce a range of related parts, using a family tool can be a cost-effective solution as the overall tooling investment is lower.
Reduced Overall Cycle Time
Since a family tool produces multiple parts in a single injection cycle, the cycle time per part is reduced compared to producing each component in a separate tool. This means that for every cycle, you can produce several parts instead of one. This can lead to faster production, especially for lower volumes or when parts are assembled together in within the cycle time making the most of your labour overhead. By reducing cycle time, family Tooling can increase overall throughput.
Reduced Production Costs
Since a family tool produces multiple parts in a single injection cycle in one tool, it only utilises one moulding machine. A portion of the part cost is machine rate rather than across several machines. Reduced machine utilisation can reduce its impact on the overall production cost to produce the product.
Simplified Part Handling and Logistics
When multiple parts are produced together in the same tool, they can be removed from the tool at the same time, which simplifies part handling. Where suitable, manufacturers can streamline post-production processes such as packaging, inspection, and shipping. This can be particularly beneficial for companies producing product sets that require all parts to be assembled together. By producing the parts in one tool, the manufacturer ensures all components are available at the same time, improving workflow efficiency.
Improved Material Usage
In a family tool, all parts share the same material, which can optimize material use. Manufacturers can reduce material waste and make more efficient use of raw materials because the tool is filled with the exact volume needed to produce all parts in a cycle. Additionally, this setup ensures uniform material properties across all components, which can lead to better quality control.
Ideal for Low to Medium Volume Production
Family injection tooling is often a good choice for low to medium-volume production runs. For companies with a diverse product line or those producing sets of components that must be assembled into a final product, family Tools offer an efficient way to meet production goals without the high upfront investment required for individual Tools. This is especially important for manufacturers who want to keep initial costs down during product development or market testing phases.
Cons of Family Injection Tooling
Part Design Limitations
One of the biggest challenges of family injection Tooling is designing parts that work together in a single tool. All parts must be made from the same material and must have similar wall thicknesses, cooling rates, and shrinkage properties. If the parts differ significantly in these characteristics, it can lead to defects such as warping, sink marks, or incomplete filling. Additionally, parts with highly complex geometries may not be suitable for family Tools due to the difficulty of accommodating different shapes in a single tool.
Uneven Part Quality
In family Tooling, different parts may have varying sizes and shapes, which can cause imbalances in how the material flows into the cavities. Larger or more complex parts may require more injection pressure or longer cooling times than smaller, simpler parts. This can lead to inconsistent quality across the parts, with some receiving more pressure or cooling than others. Inconsistent material flow can cause defects such as flashing, incomplete fills, or variations in surface finish.
Longer Setup and Design Time
The process of designing a family tool can be more complex and time-consuming than designing a single-cavity tool. The tool maker must account for multiple part geometries, ensuring that each cavity is properly balanced and that the tool allows for consistent injection and cooling.
FEA Mould Flow can assist with balancing cavities. Refer to my previous blog that looks into Balancing of Cavities in a Plastic Injection Moulding Tool.
MouldFlow Analysis to balance cavities. Balancing cavities in a tool often involves complex engineering and can lead to longer lead times in the design and manufacturing of the tool. In some cases, the upfront costs associated with design complexity can negate the initial savings in tooling costs.
Increased Risk of Downtime
If a defect occurs in one of the parts being tooled in a family tool, the entire tool may need to be shut down for adjustments or repairs. This increases the risk of production downtime compared to using individual tools, where only the defective tool would need attention. Additionally, if one part of the family tool requires significant changes or modifications, it can be difficult to alter just one cavity without affecting the others, leading to costly and time-consuming rework.
Material Limitations
While family Tools are efficient for producing parts made from the same material, they are not suitable for projects that require different materials for each part. If your product line involves components made from different plastics or requires varying colours or additives, family Tooling may not be feasible. This limitation can restrict the flexibility of your production process and may require additional Tools or secondary operations to meet material needs.
There are other options that may alleviate this requirement and allow different materials, like rotating sprue bushes, but this avenue can negate some other benefits of family tooling, but maybe more on this thought bubble next time.
Is Family Injection Tooling Right for Your Project?
Family injection Tooling offers a number of advantages, particularly for manufacturers looking to reduce tooling costs and improve production efficiency.
By producing multiple parts in a single tool, manufacturers can save money, reduce cycle times, and streamline logistics. However, the method also comes with its own set of challenges, including potential quality issues, design complexity, and limitations on part variety.
Ultimately, whether family injection tooling is right for your project depends on several factors, including the complexity of your parts, the materials you are using, and your production volume. For companies producing low to medium volumes of relatively simple parts that share material characteristics, family tools can be a highly cost-effective solution. However, for more complex or high-volume projects, the limitations of family tooling may outweigh the benefits, making it better suited for smaller-scale or simpler product lines.
By weighing the pros and cons of family injection tooling, design teams and manufacturers, by working together, can make informed decisions that align with their production goals, budget, and quality standards.
équipe design serves to help navigate the best solution for the best application by bringing together design teams and trusted tool makers and injection moulders together early in the design and development phase of a project to achieve the most optimised plastic injection moulded parts for the best possible product solution for our customers.
That is the essence of ‘Design for Manufacture’
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équipe design & consulting, with 20 years experience in design and manufacture of Medical grade moulded parts and product, including 5 years at the coal face as Operations Manager at a world class medical grade moulding facility; we are specialist in Design for Manufacture (DFM).
Please reach out if you feel you need assistance with your part design for plastic injection moulding, from Design Coaching and Guidance to Full Service Design Consulting.
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