Archive for September, 2008

How to Choose a Manufacturer and what to Expect

September 17, 2008

From your perspective you will be looking for two types of manufacturers. In the first category are those companies which will make the individual parts you need for your product. The second group of manufacturers are those who will put your product together.

All manufacturers will vary in their levels of sophistication. This sophistication will typically be a function of their current or desired customer base. For example those manufacturers who supply to the automotive, medical or aerospace industries will be required to have very rigid quality systems, controlled manufacturing processes, order entry systems and so on. Such systems are, more often than not, dictated by the customer and are a condition of doing business. Adherence to these systems on the part of the manufacturer are often reinforced by on site audits carried out by the customer. So, these types of suppliers are at the high end of the scale and will usually price their services accordingly. These systems are not inexpensive to implement and the company must recoup its costs in some manner.

On the other end of the scale are manufacturers which don’t have all of the high end systems, but do a good job within their area of skill. These companies typically will have their own means of ensuring quality. They will also be the most cost effective and will tend to treat you on an equal footing with their other customers. It will be well worth your time to visit these folks and review these items:

  • Ho w does the company take in and control your component specifications? You obviously want to ensure that each part made for you meets your requirements and that each part is identical to the next one. If a CNC program is written for your part, how do they ensure than no one messes with the program?
  • Will they make and retain a “first off” sample part? They should use this part to make any initial verifications against your specifications.
  • Do they have an equipment maintenance program? Do they have evidence that they follow that program? You do not want dull tools to be used to make your parts. If your part is a molded plastic part, how often do they tear the mold down and inspect for damage?
  • How do they plan on storing your parts? Will they be in an area which is safe from damage and the environment? How do they handle your parts once done? Do they toss ‘em in a box thus exposing them to possible damage?
  • How does the company handle your orders? How are they transmitted to the manufacturing operation?
  • How will they ensure that the raw materials used in the operation are the ones that meet your requirements?

To dwell for a moment now on those companies which would assemble or put your product together, many of the same comments above apply. You will want to find a company which has good, demonstrable control over its assembly processes. The key here is that the processes must be consistent and repeatable. If they use a pneumatic screwdriver sometimes and a manual screwdriver at other times, this is bad news. If they use a manual screwdriver (thus having little control over tightening torque) and they should be using a pneumatic screwdriver which allows for consistent torque, then that is bad news also. How do they handle your parts between operations? If there is a problem with some of the parts that go into an assembly, how they assure that only good parts are used?

In general you can expect good results from suppliers for whom you have verified references, but your best insurance is that you personally review these key process items and make certain that your chosen supplier has all of these systems in writing and that they actually use them.

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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.

Why is the Manufacturing Method so Important and How to Choose the Best Method

September 4, 2008

Why is the Manufacturing Method so Important and How to Choose the Best Method

In previous blog entries we have repeatedly noted how important it is to keep the manufacturing methods as a key focus of your design process. We mentioned DFM/DFA (Design for Manufacturing and Design for Assembly) and commented that a good design effort will be typified by bearing these two disciplines throughout the design process. Why do we keep harping on this?

There are several key points to consider. Let us assume that whatever your product is, that you will be making a bunch of them. That means that whatever initial work you put into the design and manufacturing processes will get replicated through each one you make. There are many ways to design any given product and there are many ways to make that same item. Let’s talk about the design input for a moment. Take for instance a part of a mechanism that is intended to provide friction. It does this by rubbing on another surface. You decide that the actual contact surface should be a polymer. There are two ways to carry this out. You can make the entire part from the chosen polymer or you can make another piece and fasten the friction polymer to that second piece. Either method would work, but the second method would have more cost both in labor and in part cost. It also may lead to reliability problems. Each time you add a component (and fasteners) you increase the chance of problems occurring during the use of the product. The time to consider these design issues is in the beginning, not after you are in production as you now have foolishly baked a lot of extra cost and problems into you product. Remember, it gets replicated with each one you make!! We are big on part reduction. One of our rules of thumb is if there are two parts next to each other and neither part moves relative to the other, then you probably have one more part that you need.

The considerations about the manufacturing and assembly methods follow a very similar thought process. Let’s take the example of a plastic assembly. You have two housing components that you have to join (Yes, we know that two housing parts violate our “no relative motion” rule but housings quite often are the exception to rule as you have to contain other parts within the housing). Let’s consider two ways of joining these two housing parts. You can use fasteners or you can use ultrasonic welding. If you use fasteners you have baked in the cost of the fasteners and the labor to install them (Sure, if the housing needs to capable of disassembly then the fasteners are an option). If you choose ultrasonic welding, then you have no fasteners (and you have the option of getting a water resistant seal without adding a separate gasket). You just minimized the cost of each product you ship out the door. Once again, in the design phase is the time to make these choices. One additional note here is that in the design process, each individual component of the complete product should be designed so that it can only be put together one way. This will be a tremendous aid to the manufacturing operation. Also if you can work this in, design your components so that if any one of them is missing, other components will not fit or function correctly. This allows you to catch errors in the assembly process prior to the product being completed and you are forced to toss it in the trash.

How do you choose the best manufacturing method? This is a text book in itself and would be much too lengthy to cover in detail here. However here some guidelines:

  • The method should meet the requirements dictated by the design intent of the product or part. That is, don’t use polymers where the structural needs demand steel.
  • The method you choose should be the minimum cost method that satisfies your requirements. Note that amortizing tooling cost in this is a key part of your analysis.
  • Once you choose a method, make certain that you qualify the supplier that will be executing that process. Do they know what they are doing? What is their experience with this process?
  • The method should be consistent. This means that every part that goes through the process should be treated identically to all of the others.
  • The method should be a commonly accepted practice. In other words ideally the method you use will be available at other suppliers. This reduces that chance of you being held hostage by a supplier or allows you to move your manufacturing for other reasons.
  • If you plan on implementing this method in your own internal processes, allow time for a learning curve if it is new to your production methods.

Not making wise decisions upfront regarding manufacturing and assembly will be a long term cost and possibly reliability burden to you.