Peter Atem, 32, was convicted Friday of first-degree murder and related charges.
Investigators say in February 2015, a day before the fatal stabbing, 25-year-old Danny Vazquez tried to pull a chair out from under Atem.
Following the prank, investigators say Atem told Vazquez, "I'm going to get you for that."
The following day, while working at the MOPAC Rendering Plant in Franconia Township, a witness saw Atem in a physical confrontation with Vazquez.
A short time later, investigators say the witness heard screaming and saw Atem stabbing Vazquez.
The witness tried to help the victim, who became unresponsive.
Vazquez was taken to Abington-Lansdale Hospital where he was pronounced dead.