Trouble Shooting-Proper Alignment
Good alignment is critical to obtaining long tip and sleeve life. It is required for one reason, to obtain proper clearance between the tip and the sleeve. Bent plunger rods are a common problem in alignment. The rod and tip can be easily checked by placing the assembly between centers and indicating various diameters.
The design and condition of couplers is a big factor in proper alignment as well. Non-parallel surfaces cause severe knee action when the cavity is full and force is applied. The plunger rod often bends because the end contacting a spacer is worn and not perpendicular to the rod center line. When used, spacers must have hardened load bearing surfaces and all surfaces must be flat and
parallel with one another.
Also, the shot cylinder piston rod must be in good alignment with the sleeve bore in the front plate. If the front plate bore is worn, then the clearance between it and the sleeve will be below the center line of the shot cylinder. The proper clearance between the front plate and the sleeve is .001/inch of diameter.
Concentricity of the plunger tip aids in good alignment. The OD of the tip must be concentric with its pilot diameter into the plunger rod and the threads of the tip must be square with the back seating surface of the plunger rod.