When sourcing used preform molds, the most critical technical factor is the cavity number and layout, as this must align with your existing injection molding machine's clamping force and tie-bar spacing. You must verify the neck finish dimensions (e.g., PCO 1881, 28mm, 30/25) to ensure compatibility with your capping equipment. Additionally, inspect the hot runner system (e.g., Husky, Mold-Masters, or Yudo) for electrical integrity and the cooling channel condition to ensure there is no significant scale buildup that could impede cycle times.