What are the design reviews typically carried out during the new product design, development, and manufacturing process, and when do they take place? These reviews are an important piece of the puzzle for reducing the risks of reliability issues and defects in your products, as such you will want to implement them.
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Why design reviews are important.
Getting early feedback on your new product design from experienced parties or those who have relevant experience is a must. They can check what you are planning to do and consider the risks and other implications.
The goal of a design review is to identify mistakes or elements that have been missed when you’re planning the product concept early on, as the cost in time and money to fix it then will be minimal. If you find that you have overlooked something later on, such as when CAD drawings have been made, that could be a few days of design work down the drain. Worse still, would be to make changes after product development has been done or after tooling has been made, perhaps because a customer finds fault with the design in your late-stage prototype, as this could lead to months of work being wasted or even tens of thousands of dollars worth of steel molds being scrapped! (02:25)
The different types of design reviews and when they’re done
Phase 1. Early stages
Someone assumes the role of product manager and documents the product’s requirements (what should it do, minimum performance levels, etc), and translates these into engineering terms.
Then you need to get ‘design inputs’ from various sources where they find risks and issues, such as the plastic selected not being durable outdoors in the long term when exposed to the elements, and these inputs will influence the design. The people reviewing the design at this point should be target users, product designers, industrial designers, mechanical or electronic engineers with experience in that type of product, someone from manufacturing, and maybe even from logistics.
A good example of why opinions about the product design from many sources are useful early on is that a logistics person could look at it and suggest that if it’s being sold on e-commerce it will not fit in a standard FedEx package. Therefore the design input from this would be to design the product with shipping in mind. There are many DfX approaches you may take to focus on what’s important for your product while you design it. (12:02)
Phase 2. Proof-of-concept and feasibility study.
You start to put things together crudely in order to get early feedback on a tangible product. Maybe only a rough proof-of-concept prototype can be made at this point, such as using half of a competing product modified with boxes or programming an Arduino or Raspberry Pi, so the product’s basic functions can be checked and any issues can surface. A few possible designs may be made, and you’re deciding on the design’s architecture, such as which chipset is adapted to the product’s needs. (See a past article about “prototesting”.) If you find later that you made a mistake with high-level architecture you’d need to return back to this point.
An experienced design engineer should review the initial design now and they will ask questions, suggesting some ways to improve or avoid issues as they see them. This is a very helpful investment at this point, more so than paying a lot of money for patents, for example. However, some businesses are worried about revealing their product idea to anyone, so they skip it, and they miss out on a wealth of experience. (17:18)
Phase 3. Design FMEA when the design starts to take shape.
You now have the product’s architecture, answers to some of the big foreseen challenges, and a relatively clear idea about what you need to do. The engineering design work needs to be done, and prototypes made and tested, until you have a final tested and approved prototype.
During this complex process, many questions about how to proceed will arise and different engineers will have different opinions, so having another design review is helpful. A design FMEA is a structured approach to risk analysis that can be used once the product design has started to take shape. Each of the product’s modules is considered as to how it can possibly go wrong and the risks ranked by probability of occurrence & severity by people with different perspectives: design, manufacturing, the business side, etc.
Based on this you can identify a priority list of risks to handle which may require design changes. For example, the product may be fine for use as a garden tool, but someone identifies a risk to children because it looks fun and like a toy. This is a serious risk that will need to be fixed, perhaps by redesigning the product to look less appealing to kids. Since you are still in the product development stage, any changes a product review instigates at this point are more manageable than once the design is locked, say, and tooling is fabricated.
When testing functional prototypes you need very specific expertise and will need to take into account feedback from manufacturers. For instance, a specialist surface treatment supplier can feed back to you whether the surface processes you have selected, such as PVD coating or electroplating, are a feasible choice for the type of product you’re making. (22:22)
When to do Design for Reliability / Manufacturing reviews?
These design reviews will ideally be done early as soon as you have some kind of design, even if they are just sketches or CAD drawings. For example, if a product must be reliable and keep on working as a matter of life or death, then you’d look at what kind of redundancy the key elements like a motor have. The motor may statistically be somewhat reliable, but by adding a second independent motor you add redundancy and reduce the chance of the whole product failing (like planes having more than one engine), and this is a typical DfR decision that influences product design for reliability’s sake.
But then a DfR validation will also be done again later during the testing and validation phase of the new product introduction process, and a reliability engineer will examine a tangible prototype/s with a reliability focus and put it under various stresses to see what it takes to make it fail and whether that is within the reliability targets for the product (and/or computer modelling may also be used for this validation). (28:47)
Process FMEA just before the design is locked and tooling is made.
Before you commit to the design and get expensive tooling fabricated, it’s always safest to do just one more design review. Getting the manufacturer to assemble the final prototype so they fully understand the design and assembly method and can check for issues with manufacturability and in the processes is a good idea, as is getting an experienced product engineer to check the design and manufacturing aspects and consider what could go wrong.
Doing this in a structured manner calls for a Process FMEA where the assembly and process plans are checked and possible failure modes are found and fixed, such as the risk of an assembly operator plugging a wire into the wrong location. In that case, a test on the assembly line after the operation could catch such a mistake and avoid defective products being manufactured, for example. The findings from the Process FMEA will be an action list to be worked on with the manufacturer before production can start. (34:08)