Aluminum alloy 5052 / 6061

3003 is the most formable of the alloys mentioned. it's used lots for sheet metal interiors, tanks etc. min bend radii of 1t and (in the UK) cheaper than 5052. 5052 has better mechanical properties but is not quite as formable- more suitable for light duty brackets but can be used just as 3003

normal tempers are 3003-H14 and 5052-H32. if you need to do any complex forming (say, hammerforming compound curves) either can be annealed by coating the area (to be shaped) with soot from an acetylene flame and then heating until the soot burns off. after shaping you'll be back to about half hard (H14) condition.

FWIW 6061 can be bent successfully provided a suitably large radius is used- aim for 3t.

321 is the best stainless alloy to use for exhaust headers, it's less prone to cracking at high temperatures than 304. having said that 304 seems to hold up OK in normally aspirated applications. i've heard some comments that 304 is not up the job (and seen/repaired some cracked 304 headers) but personally i think it's down to poor fabrication techniques

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Injection Molding: Troubleshooting

Approach to Troubleshooting

Proper troubleshooting should use a systematic approach to resolve problems. There are two kinds of issues: those involving "quality control" and those encountered during startup.

"Quality control" issues occur when parts have been successfully produced in the past, but are now out of specification. These problems are the result of something in the process changing.

To resolve them, one must determine what has changed and restore the process to its proper balance. Startup problems occur during the launch of a new tool or machine.

Quality Control Issues

Most quality control issues are caused by process conditions, the material, or machine and tool maintenance. If the problem occurred after a change in the material lot number, try a different lot of material. It is advisable to store a retain of the previous lot of material.

If the mold setting is from a previously successful part, check the original setup conditions. If the mold is used in a different machine, minor adjustments to account for the new machine may be needed. If the mold was modified during its downtime, process adjustments may be required.

Startup Issues

To resolve startup problems, the material's process window must first be determined to ensure that there is a set of conditions that can make good parts.

Start by setting the process conditions to the middle of the material's process range and then adjust the process to fix any observed problems. If successful parts are not possible, determine what combination of variables must be changed to resolve the problems. These changes may include material selection, machine selection, and/or tool redesign.