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How To Measure The Wear Of A Barrel

1. Clean the barrel of any remaining plastic or foreign objects. This should be done while the barrel is still  warm and can be easily accomplished using Services for Plastics, Inc. Bore Brushes, Bore Brush Extension Rods, Abrasive Pads and Copper Gauze.

NOTE:  A bore gauge that still contains plastic can damage the measuring head of a precision bore gauge.

2. Once the barrel is clean and cooled to an ambient temperature, complete the top two portions of the Customer Barrel Inspection Form. Be sure to provide as much information as possible including dimensions and counterbore type.
3. Select the bore gauge extension that matches the bore diameter of the barrel and apply to plunger on bore gauge.
4. Set micrometers to match the original dimension of the O.E.M. bore diameter (+0.001" for tolerance allowed). Hold the micrometers on the plunger of the bore gauge and adjust the bore gauge dial to set bore gauge to zero. Remove micrometers. Repeat this step to ensure accuracy of set up.

WARNING: When performing a field measurement with a barrel still on the machine, DO NOT measure the barrel bore behind the feedport.  All critical wear that affects the performance of an injection unit is on the endcap side of the feedport.  Severe damage can occur when the measuring head enters the feedport of the barrel.

5. Using a tape measure, measure the distance from the end of the barrel to the approximate position of the feedport opening.  This distance is the maximum allowable distance that the gauge can travel into the barrel without the measuring head entering the feedport.

NOTE: YOU WILL NOT TAKE MEASUREMENTS IN THE FEEDPORT. Leave up to a 2" gap between the gauge and the feedport. Instead of the feedport, you should concentrate on the stroke area and the transition section of the barrel. This is the major area of concern.

6. Place the plunger end of the bore gauge in the discharge end of the barrel until the plunger touches the outside edge of the pilot end of the barrel. Extend the gauge slowly into the barrel bore until desired depth is reached WITHOUT entering the feedport.
7. Using 1" increments, pull the bore gauge toward the discharge end to measure and record measurements in the BORE MEASUREMENTS section of the Customer Barrel Inspection form.

Remember:
Always clean the barrel thoroughly prior to measuring.
Allow barrel to cool to an ambient temperature before measuring.
Move the bore gauge slowly to ensure proper measurements and avoid damaging the bore gauge. 

Do not apply oil to the bore gauge or barrel.
Do not push or jerk the bore gauge.
NEVER put bore gauge into a hot barrel or a bore containing plastic.