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DFM | Multi-component


Two-component insert moulding


Estimated manufacturing cost: €0.32 - €0.36 Typical sales price: €2.50 - €3.50


Mono-component insert moulding with tampon printing Estimated manufacturing cost: €0.25 - €0.28 Typical sales price: €0.75 - €1.00


Figure 2: Comparison of estimated manufacturing cost and typical sales price for mono and multi-component toothbrush produced by insert moulding


Two production scenarios were considered and benchmarked prior to the start of the project. The fi rst was to apply soft paint to the moulded part in a post processing step, while the second was to use a multi- component moulding technique. The most important requirements for each scenario, as well as their advantages and disadvantages are laid out in Figure 3. While the tooling and moulding equipment cost was


considerably higher for the multi-component option, the elimination of the labour intensive painting process provided a big saving. In fact, an overall annual saving of around €120,000 was estimated if the multi-shot solution was adopted. While the multi-component tooling and process is more complex, a risk anaylsis determined that the multi-shot scenario was manage- able with regard to any expected quality issues. However, it does need to be emphasised that this risk can only be managed by investing a bigger upfront effort


in Design for Manufacturing (DFM) during development of the multi-component product design. The example in Figure 2 shows how multi-compo- nent moulding can help lift a product so it can be sold in a higher price segment. In this case study, the replace- ment of tampon print decoration on a single-piece injection moulded toothbrush with a well-designed two-component alternative adds only a slight premium to the manufacturing cost but almost doubles the typical retail price that can be achieved. It can be seen that the cost, design and functional


benefi ts of multi-component moulding makes the technology very attractive across all industries. The downside is that the component design can become very challenging, making it diffi cult to accomplish a good, reliable and cost effective moulding process. The following list details the 10 most important points that need to be taken into consideration while


Figure 3: Comparison of post-moulded painting and multi-shot moulding for production of a phone cover PAINTING


Requirements Advantages


Single component moulds for PC/ABS component Less complex tooling Painting masks


Storage, shipping & part handling Paint and painting cost


Lower overall tool costs Low risk of part distortion


Suitable for production in low labour costs Low technical standards


MULTI-SHOT Requirements Two component moulds Advantages Disadvantage


No post processes or additional labour required More complex component design Improved tactile surface fi nish Potential production cost reduction


Higher capital cost on tooling and IM equipment


Research on material pairing for good adhesion Higher risk of distortion More effort on upfront DFM


48 INJECTION WORLD | January/February 2013 www.injectionworld.com Disadvantage


High labour and side costs Additional cost of painting


High scrap rate expected in production due to paint quality issues


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