We got a order of tube machined parts from a Canadian customer in October,big diameter with 65″ long,C1020 material, OD 8″ x 0.75″ wall, it’s difficult to buy this inch tube in China,unless make mold specially,but the MOQ is 10T.
The offer we provided to custoer is based on OD8 x0.78″ with out machining inner diameter.When we book the raw material HRS tube,we found the surface of inner diameter is very rough,with rusty black skin,it is not possible to used for precision machining parts if the inner diameter without machining.
Rough Surface of HRS Tube
Smooth Inner Surface of Grinding Tube
We have difficulty now,it is easy to machining OD ,but we don’t have ability to machining ID for so long tube.Due to complete this project for customer,we began to search the tube with smooth inner surface.It is called grinding tube,rough OD and smooth ID.Material cost twice as much as HRS tube.The inner diameter is bigger 0.08″ than HRS tube. After confirmation of the dimensions changing with customer,we start working on it.
Some area of outer diameter not processed
We found a new problem in the process,since the thickness of grind tube is uneven,the difference is about 0.078″,so there is somewhere of outer diameter not processed,if increase the tool feed,the smaller diameter will be obtained and the wall thickness will be thinner than the tolerance requirement of the drawing.Communicate with customer again,we get instruction is that make sure the dimensions and ignore the appearance,the area of outer diameter were not processed will be polished by hand.
One month, we finally finished this project, although no profit, but we completed the order.In business, honesty is more valuable than money.Through this project, we have deeply realized that the earlier quotation work needs to be more detailed,especially for tube machined parts,we should know more details of raw material,such as the tube specification,surface roughness of tube,dimensions tolerance.
If the engineer can consider the existing specifications of the market materials in the design,Design reasonable size according to the application demand of the product,Will reduce material cost and processing cost.
