Materials and Processes Specification

[avior]

A change just arrived,
was:
- Shop life - 40 dasys
is:
- Shop life - out time 15 days, mechanical life 40 days

what means "mechanical life 40 days"?

 

[SWComposites]

In general:
Out-time is time the material is out of the freezer until it is encased in the final vacuum bag for cure.

Mechanical life is the time the material is out of the freezer until it is put into the autoclave/oven for cure.

The change essentially requires the material to be laid-up within 15 days, but it can sit under a vacuuum bag out of the freezer for another 25 days until it is cured.

Some details related to these definitions vary between spec's.

 

[Compositepro]

The description above is correct although from a different perspective than the way I think of it. Shop life is the allowed time out of the freezer where the material still has adequate tack to be used for laying-up parts. The mechanical life is the allowed time out of the freezer before cure where the advancement reaction of the resin has not gone so far that it will affect the mechanical properties of the finished product. These actual times depend on a number of factors, particularly room temperature.