Products Designed for Production

By Martin Spencer, UniqueRoto

Over the next few months, I intend to use this column to introduce and discuss various ideas and tips to help you take a more lateral look at your production techniques for rotational moulding. Some will be very simple ideas, and others will be new techniques altogether. Several aspects of the process will be covered in future articles but please contact me through the magazine if you have specific questions. My plan is to inspire you to look at what is happening on your shop floor and how it could be improved.

It is never too early in the process to consider how a product will actually be produced. Efficient production should really start at the product conception stage. If a product is to be produced by rotational moulding, then at concept all stages of production should be considered. However, it is important to ensure that production requirements do not curtail design freedom and innovation. I have seen many examples of inflexible production requirements restricting the designer which ultimately created a product that fell short of the customer’s vision. Design and production should work in harmony to create a product that satisfies all the customer’s requirements whilst still being efficient and economical to produce. The strength of the relationships between designer, moulder, toolmaker, material supplier and customer can have a significant impact of the output and are certainly worth building!

The use of a product design and production checklist to follow the lifeline of a product from concept to first delivery can be very useful. The checklist should contain points under a series of headings such as design considerations, tooling, production on the machine, finishing, packaging and delivery. Within design considerations you should think about:

• What is the product being designed to do?

• What is its target market?

This will affect the design, surface finish, material choice, pigment type, decoration and the method chosen for toolmaking.

• Will inserts be required?

• If so, what type?

• For what purpose (decoration or load bearing)?

• Will the design work with the material chosen? (FEA analysis and/or physical tests)

• What colour will be required? This can affect material price but also which machine you schedule production on (e.g. white and black products may not run on the same arm/machine due to cross contamination).

At the conception stage it is wise to get the potential toolmaker (or initially several toolmakers) involved. What is the best tooling method to suit the potential market, the product shape, surface finish required and any likely combination of tools on the arm/ machine?

Once the toolmaker has been chosen they should be involved in the placement of split lines and vents. What surface finish is required and what type of release agent will be used? Thought will need to be given to how you will mount the tool, how it will be clamped, how will it be loaded with material and the method that will be used for demoulding. How often have you seen tools arrive for production that then need alteration to be able to mount and run successfully on the chosen machine?

Once toolmaking has been resolved then initial stages of production planning needs to start. Will the product have a dedicated arm or will it need to run with other products? Will cycle times, rotation ratios, oven temperature and cooling cycles be compatible? Will the tool be loaded whilst open or through a loading port after assembly? Thought will need to be given as to how the product will be demoulded and if jigging will be required during post tool cooling. Has the customer specified critical dimensions and tolerances? How will these be maintained? I am sure we have all experienced a customer tolerance requirement that only comes to light once the first prototype is delivered. The customer will need to specify how many prototypes are required for approval, testing and pre-production samples. Then what batch sizes have been agreed for production deliveries?

Once the product has been moulded, how will it be finished needs to be planned. Split line positioning and design is crucial to easy high quality trimming. If the product needs holes or apertures, can these be moulded as part of production rather than become an extra finishing operation? Can the product be designed to be finished by the operators as it comes off the machine or will it require specialist operations in a separate finishing department? What additional post moulding operations will be required and can these be designed out or streamlined at product concept stage?

Once you have a finished product how it will be delivered needs to be decided – in large batches to the customer or singularly to the end user? Packaging needs to be designed appropriately and sufficient storage area allocated.

If all these aspects can be discussed and decided upon at the concept stage of the process and incorporated in the design checklist for the product, then the design can develop in a structured way hopefully ensuring no (or at least minimal) last minute surprises when production commences. Major projects can take many months if not years to progress from concept to reality but the more effort that is put into planning at the concept stage, the smoother and hopefully the more successful that journey will be.

So, if you have a product design checklist now is the time to review it and if you do not have one yet I would recommend that you create one. It is the ideal way to bring all the expertise of the customer, toolmaker, material supplier and moulder together to create a winning product.

from an article at RotoWorld®
https://rotoworldmag.com/products-designed-for-production/