Donald, a hydraulic valve customer from the United States, recently had an order for hydraulic valve sleeve parts with an old supplier. It took more than 30 days to adjust the approval sample of hydraulic valve sleeve for many times. The taper of hydraulic valve sleeve always failed to meet the customer requirement of 0.3-0.5m. The manufacturer can only give up the order, but this wastes Donald's time. The trouble is that the customer is still urging the progress of the modification of the hydraulic valve sleeve. Donald consulted more than 30 hydraulic valve manufacturers online, but none of them can guarantee that the taper could reach 0.3-0.5m. Only 2 manufacturers indicated that 1-2m is the limit that they can reach. Donald plans to give up this hydraulic valve sleeve order, but he doesn't know how to talk to the customer. While Donald was worried, his colleague Smith gave him the contact information of AAK HYDRAULIC VALVE. Smith had inquired about the hydraulic valve with AAK before. Smith directly emailed us the inquiry requirements and the drawings of the hydraulic valve sleeve, and CC Donald. He asked us to communicate with Donald directly to see how to solve the taper requirements of the hydraulic valve sleeve. After our technical department had a meeting, they found that it was really a bit tricky. At present, they are not sure to tell the specific accuracy of the taper of the hydraulic valve sleeve. Except for the taper of the hydraulic valve sleeve, the straightness and roundness can fully meet the requirements. We can study the taper of the hydraulic valve sleeve while proofing. However, the specific parameters still need to be determined until the final samples come out. With a try attitude, Donald asked us to start sampling the same day. A week later, we sent out the samples of the hydraulic valve sleeve. A few days later, Donald asked by email if we could try again to improve the taper accuracy of our hydraulic valve sleeve from 0.8-1.2m to 0.3-0.5m to meet the customer requirement. AAK technical department made modification and adjustment for 3 days and 2 nights, and sent the modified sample of hydraulic valve sleeve on the 4th day. Donald soon informed that the parameters of the second hydraulic valve sleeve sample of AAK met the requirements. Donald is curious that more than 30 hydraulic valve manufacturers can't achieve the taper accuracy of hydraulic valve sleeve. How can AAK achieve it by making samples only in two times? As a precision part, the precision of hydraulic valve sleeve is guaranteed by operators and equipment, especially precision grinding is very important. For most hydraulic valve manufacturers, the length of the grinder they used is basically an extended grinder with a hole length of 120%. Although it can repair and maintain the hole straightness, the accuracy of the hydraulic valve sleeve can only be controlled at 1-2m maximum.