I do some work for a friend, and he has asked me to look into changing some parts from sheetmetal to plastic for possible production. I do not have any knowledge of how a part is considered to be compatible (with some changing of design) for production in plastic. I thought I would post on this forum to get some direction on how to proceed. I have discussed this one time with a plastic company (to remain unnamed) earlier in the year, but did not gain any ground. after 4 weeks of non response, they finally notified me that they were not interested. I have the parts models, we have had a few sets formed up, but an issue was raised about producing in plastic would be considerably cheaper. Thanks in advance to any and all that would be willing to shed some light.
David,
Listen to Anna and Kelvin. These look like they would be easy to supply as sheet metal parts and a bit of a pain to turn into plastic.
The long tubular part would be easy to do as a plastic extrusion, but you need to machine all of the holes in, just like you would in a metal extrusion.
The bracket parts could be molded, but you will need slides to generate the holes and a lot of thought will need to be given to wall thickness and draft requirements. If you need the stiffness of the 1/16" steel, you will need much thicker walls in any plastic and careful thought as to which plastics to use. A typical unfilled plastic has about 1% of the stiffness of steel. A highly filled material might get you to 5% or 10%. You will probably find that you need to change the geometry considerably to make the design work in plastic.
Depending on the quantities that you are going to be molding or stamping, you will probably find that the plastic tooling is more expensive up front. You might or might not get low enough part costs to make it pay.
Jerry Steiger