Last month an Indian customer ordered a batch of tungsten carbide valve seats from our company,after our company shipped the products on time, the customer sent messages that our company's outer diameter was out of tolerance and did not meet the requirements of the drawing, which made it impossible to match their steel housing.
According to the drawing,there is a conical angle on the value outside diameter. the outer diameter of the large end is 32.05mm and the outer diameter of the small end is 31.05mm,the customer sent the measurement result, which was not 31.25mm, and stated that the diameter of the small end of all valve seats was between 31.25-31.28mm.
After receiving the information, our company attached great importance to it and immediately confirmed the test results before delivery with the quality inspector. The quality inspector replied that all valve seats passed the full inspection. Because there were several extra tungsten carbide valve seats in the warehouse, we re-monitored the valve seats with a two-position detector and found that the diameter of the small end was 31.08mm, which was within the tolerance range +/-0.05mm required by the customer.
Why is there such a large detection difference on inspection for a same batch of tungsten carbide valve seats?
The inspection tools used by the customer were vernier calipers and micrometers. These two measuring tools often produce large deviations when measuring some tapered outer diameters. These data should be inspected with a two-dimensional or three-dimensional detector.
Since the valve seat provided by Oston Carbide meets the requirements of the drawing, why can't it be used with the customer's outer frame? It turns out that the drawing of this carbide valve seat was also drawn by the customer using a vernier caliper for physical inspection, which makes the size difference between the drawing and the actual object. Oston reminds you that when the tungsten carbide product has a tapered angle, we should draw the drawings based on the angle,and if the outer housings have been produced, we recommend that the valve seat need a negative tolerance to ensure that it can perfectly match the outer casing.
As the goods have been shipped to India, even if the customer is willing to pay us to refinish them, the returned goods will face high import and export tariffs and international shipping costs. The customer finally finished the steel housing so that they can be matached normally.
For more information about cemented carbide, please visit the OSTON official website: www.ostoncarbide.com
