Back in the days when I was the Quality Assurance engineer assigned to the Engineering Department, the chief Manufacturing Engineer talked them into making some of a production Auxiliary Power Units aluminum housings using a low pressure Permanent Mold process.
He had worked at Mcculloch Chain Saw where most of their engine parts were either die castings or low Pressure Permanent Mold castings. He maintained this change was supposed to save the company millions of dollars.
After spending a fortune to make the dies and to test the new parts they were put into production.
One day I was called into the Chief Engineer's office. Laying on his desk was one of these housings.
He said, "Jim, your QA department says this is a good part. What do you have to say about it?"
I said, "If it passed inspection, it's a good part."
He said, "We were going to install the screw thread inserts into it but one of our mechanics refused to do it. Take a look into the threaded holes and tell me if he was justified in his refusal."
I looked down into the holes and saw good threads running about .150" (3.8mm) deep. The majority of the rest of the threaded holes consisted of sponge like metal with an occasional bit of threaded solid metal.
Needless to say, the part was junked and the company had to spend another small fortune recalling the engines that had been shipped with these LPM parts.
The LPM parts were replaced with old fashioned sand cast parts.
I'm not saying that LPM and die cast parts can't be useful. In their place, they can be strong enough to work quite well but they do have some problems. Welding them is one.