Availability

One of the first things that several designers ask when primarily considering the use of a particular material is whether the material is on hand. A "no" answer shall provoke a second question: May we get it in one week? Two weeks? And so forth. If this answer is acceptable, the next question is, Do we have to order a minimum quantity? There are more than 15000 types of plastics that are commercially available, but just a dozen or so are available in standard shapes from warehouses. How available is the plastic under consideration? Is it available just in the form of molding pellets?

Another pertinent question: Is the material available from more than one supplier? This is not advisable to utilize a proprietary material that is available from just one supplier if it is likely that the parts in question shall be made again five years hence. The same thing holds true if several parts are required. If you are a captive buyer, and you are at the mercy of the supplier as far as cost and delivery schedules are concerned.

Sometimes a raw material fabrication technique might limit availability. As an instance, it is not uncommon to obtain delivery times of 40 weeks on special forging. In lean times, castings might be obtained in 4 weeks; in some of the cases delivery times can be 12 weeks. These are all important selection factors under the category of availability. It is the designers responsibility to establish a time limit for the procurement of materials, and if a desired material cannot be attained within the constraints of the schedule, another material will have to be substituted.