Archive for the ‘Uncategorized’ Category

Assembly Methods for New Product Design

May 26, 2009

What means should I use to assemble my product? When we talk about assembly we are covering a couple of areas. We are referring to the methods we use to fasten one part to another and we are also talking about the processes used in the production of the item. Let’s do this one more time to ensure that we have this clear. In one respect we are considering the means of fastening parts. That is, are we using adhesives or screws? In the second respect we are covering the production process or tools used to perform the actual assembly. Are we using a manual screwdriver or a pneumatic driver with auto feed?

To be sure these two considerations are intertwined, will have a significant impact upon the quality of your product and, like many things we have discussed previously, need to be determined up front. How are they intertwined? Let us assume that your product will have a high production volume. That would drive you to use a fastening method that could be accomplished quickly and efficiently in production. If you have the choice between an adhesive then, or a screw, you would then opt for the screw as it is more conducive to quick, consistent and reliable fastening. (Yes, I know that there are a number of people reading this who are pro-adhesive. I have spent years working with both methods. There is a place for adhesives. They are unique in their application and serve a role that other fastening methods just cannot fill.)

How will the assembly method have an impact on the quality of your product? Let’s look at the use of a screw. There are several ways in which you can install such fasteners. Let’s look at the use of a manual driver as compared to the use of a pneumatic driver with the ability to set torque. As diligent as a person might be, when using a manual screwdriver they simply cannot tighten the fastener as consistently as someone using a settable pneumatic driver or electric. The end result will definitely show in the quality of your output. It should also be obvious by now why the assembly method needs to settled upfront as an integral part of the product design.

OK, what are some of the means we can use to fasten parts of a product together?

• Fasteners such as screws or snap clips

• Adhesives (cold, hot, UV cure, and so on)

• Ultrasonic welding

•Heat staking

•Molded in features such as snaps


Moving these methods to the production realm requires you to consider things such as consistency, reliability and durability (validated through your product testing process), ease of installation and cost. The costs to consider are not only the cost of the fastener itself but also the cost of the assembly equipment. Ultrasonic welding is a good example of this. There is no fastener cost as you are simply bonding the native materials together. But, behind the curtain is the cost of the welder itself, the horn used to focus the weld energy and the cost of the fixture to hold the parts while welding. This can run up to $30,000 and is certainly not the method you would use if you were only making 20 parts a year. Here come the adhesives!!

How do I Get a Prototype Made and Why do I Need One?

September 4, 2008

How do I Get a Prototype Made and Why do I Need One?

Prototypes are a key part in any product development activity. I have yet to work with an engineer who does not see the value in prototypes. By the end of this discussion I hope that you will also see that same value.

What is the purpose of the prototype? In general a prototype provides confirmation that your product design is as you wanted it. Computer solid modeling is a huge step forward and eliminates many areas of concern, but it is not uncommon to find problem areas once you get a real part in your hands. Engineers, when introducing a new design option will even step back and build a “proof of concept” prior to entertaining a prototype. The proof of concept focuses on that one design feature that is new and is in need of evaluating further before it gets set in a prototype. I have often seen that a prototype will be used as a sales tool. In one recent instance the client liked the prototype so much that he had it painted and dressed up like the final product to show his customers. It looked very representative.

When should a prototype be made? Let’s talk for a minute about the various natures that products make take on. Some products are simply a minor variation on an already existing and validated product. A judgment call can be made at this point to make or not make a prototype. I would err on the side of safety when at this decision point. A few hundred dollars spent on a prototype could save tens of thousands of dollars downstream. You do not want to get your first manufactured parts in your hands (after spending $50,000) on tooling and find that the part is wrong!! As you ramp up the ladder toward a whole new product design, you will be faced with the decision of having a prototype made at various stages. At the extreme of an entirely new design, with no vestiges of a previous validated product, you will assuredly want a prototype. And, obviously, you will be prepared to make the prototype once the initial design is completed. In most cases, the organization making your prototype will need either computer generated solid models or drawings or both.

How do you get one made? There are a number of ways to make realistic prototypes. The key is to make the prototype of the materials (and possibly the processes) that are close to representing the final product. If your final product is made of metal, then a qualified machine shop will be able to fabricate one. If your product is to be made of plastic then you can also have it machined, rapid molded or you can choose one of the more gratifying tools in the product development arena. This tool is called “rapid prototyping” and it is gratifying because you can have a prototype in your hands in just a few days. There are several such services in most major cities. This process uses a variety of machines that operate in some cases like a printer that uses plastic instead of ink and in other cases uses a laser to remove the unwanted material from a block of material to reveal the final part. In most cases a part from this process can be handled roughly and can be quite representative of the real thing.

In some cases you will want to go a step further and obtain a prototype made of the exact materials and processes as the final production intent product. Having such parts also lets you get a head start on product testing and even lets you get a few “actual” parts in your customers hands well ahead of the timing for production intent tooling and at a much lower cost exposure than full blown tooling. If you are looking for a “real” injection molded part, companies such as ProtoMold can do this for you in a surprisingly short period of time and can also provide several hundred parts. The caveat is that you will not get thousands of parts out of these molds and you will pay more for each part. If die cast aluminum is your final material selection, there are companies such as RapidCast that can deliver these types of parts in a shorter period of time than hard tooling and the same caveats apply..

Once again, the goal of a prototype is to replicate the critical fit, form and function (and perhaps appearance) of the actual production part so that you can see the “surprises” before you put a lot of time and money into it.