Part Proliferation, Why it takes away your competitive edge? Part 4: Raw Materials

Last blog we looked at fasteners and how their proliferation affects your bottom line. In this blog we will look at Raw Materials. They have a direct impact on design, supply, and manufacturing total cost when standardized. If not standardized, it can drive up the total cost of your product.

An Aerospace company kept buying aluminum extrusions that had a minimum buy condition attached to them, and never seemed to deplete the stocks because every Engineer/Designer unknowingly specified different extrusions. However very close in dimensions, the extrusions were still different, therefore were ordered under different part numbers.   

If unchecked, raw materials can easily clutter a material storeroom. This clutter is created by the Engineers’ and Designers’ lack of visibility on what is in stock. Typically the choice of material will stop at what meets the immediate design need without regards to what is in stock, which in most case could do the job just as well.

Influence of Raw Materials,

Raw materials come in all shapes or forms that will later be transformed into components then be part of a product. Regardless of the industry, Raw Material can easily account for about 30% of the total cost of a component. Obviously, having our Aerospace Company as a scenario; inventory cost will be added over the already existing 30%.

Raw Materials are mainly classified by Format and Chemical Composition (or alloy in the case of metals, or essence for wood). Every variation of Format and Composition will generate a different material, therefore a different material stock number. Using our Aerospace Company as example; although the extrusions were aluminum alloy and shapes were the same, the extrusions shapes were of different dimensions, most of the time small differences. If the Engineers/Designers would have been aware of what was in stock, they could have designed their components around one single extrusion, thus avoiding the thousands of dollars in inventory. 

Considerations in selecting Materials

From what was discussed above, it is very obvious that one should select a raw material that is stock in the factory. However if what’s in stock doesn’t work, before selecting a material, consider the following:

• Number of parts that will be fabricated: Part volume can drive the selection of material format, as well as the transformation process.
• Availability of the material: Exotic materials are expensive and create delivery problems and are likely to have a minimum buy clause attached. Common raw materials are generally available and delivered within 24 hrs.
• Make from: Can existing parts be used as raw material and modified to suit the need? This will save time in design and minimize inventory.
• Corrosion: What are the environmental conditions? Are you dealing with dissimilar materials that can generate galvanic corrosion?
• Stress:  Vibration, creep, fatigue, strength, cracking, etc...
• Toxicity: Some materials generate toxic fumes when processed, e.g. beryllium copper.
• Dimensional Stability: Dimensions can be affected by temperature change, humidity levels, etc.: e.g. wood expands under humidity, Stainless steel warps when welded, etc...
• Transformation Process: Machinability, weldability, Formability, e.g.: Some aluminum alloy cannot be welded; Stainless Steel has poor Machinability, etc...
• Surface Protective Finish: Can it be avoided? Some metals do not require protection. Stainless steel can replace a painted carbon steel part, and will save the costs associated with painting parts.
• Environmental: Chemical transformation processes are harmful to the environment. Think green when you select a material or when specifying a Chemical process.

Raw Material initiatives

Raw material selection is done at the Design Process level, therefore should be defined as early as possible, and should be kept as much as possible to what is stock or easily available. Designers are solely responsible for material selection, and indirectly define the manufacturing process by design. This is the main reason why manufacturing and Material Management need to be involved early in the design process in order to design manufacturing and material management into the product. This exercise will also help defining a preferred raw material list.

The Ripple Effect

Having a preferred material list will have ripple effect on engineering activities, as well as purchasing and manufacturing. Having engineering use company standard raw materials minimize design uncertainty of using a new material which very often require testing and certification. It will minimize material shortage and having to buy materials with a clause of minimum buy. It will also maximize savings since the same material can be purchased at a higher volume. Manufacturing will be more stable since the mechanical behavior of the company standard material used are known and controlled. At the end of the day, it will help minimize the design and manufacturing life cycle.

Closing Comment

Raw materials are often taken for granted and the selection is done by Engineering with little regards to the production process that follow. This is not done maliciously, but  it is the result of a lack of visibility very often not given to Engineering as the everlasting motto is still being used; Engineering defines the WHAT, and Production defines the HOW.  Engineering and production function should define the materials concurrently so availability and manufacturing process stability is designed into the product.