In my quest for more source material for Ultimate Destruction SFX Library I took a quick trip to the local metal recycling facility to see if they would allow me to record. They were super nice and loaned me a hard hat and said “stay out of trouble” The only interesting activity they had going on was some scrap aluminum bundling. This giant machine is belt fed with scraps of metal and after they tumble down the chute into the compactor they come out in a fairly large size rectangular hunk of metal.
I was able to position the MKH-8040ST microphone just inside the top of the chute and get the pieces falling in and being mangled. The machine is powered by an large electric motor and hydraulics which produce a very loud whine and hum. Since the mic was just inside the chute, the motor noise was minimal. This machine was extremely loud when the metal was falling in. Since I had to wear a hard hat I could not wear headphones, only earplugs. Good thing I did not monitor the recording with headphones as I’m sure hearing damage would have occurred.
The sounds this machine made were awesome! Most of the time the belt would continuously feed hundreds of pieces of metal into the compactor so it sounded like one long, drawn out metal crash, perfect for sound design. The metal pieces were not that heavy so the resulting sound does not have much low frequency information but when a larger aluminum chunk hit the side of the chute, it was great.