Determine whether there are residual debris inside, or empty by shaking hands and check for debris inside the workpiece, if detected, continue to blow and vacuum plastic debris usually times.
Sure, there are residues or by shaking inside the workpiece. Check for and remove debris if the workpiece is detected to be blown and sucked scrap plastic again.
Check that the residue inside.? by shaking the workpiece. And hand check internal debris piece if it detects the blowing and sucking plastic scrap again.