CNC metal spinning machine assembly and processing is complex, how to assemble and process to meet the higher accuracy is very important. This article will introduce the manufacturing and assembling technician of CNC metal spinning machine tool.

1. Casting bed processing

● Material selection‌ : The bed is usually cast from gray cast iron material. Gray cast irons such as HT200/HT250/HT300 enhance their resistance to deformation by increasing the pearlite content to over 85%.

● Wall thickness design ‌: Choosing the appropriate wall thickness is an important issue in bed design. Too thin or too thick wall thickness will increase the difficulty of casting.The junction of the rib plate needs to be rounded to reduce stress concentration, too thick wall will increase the materials cost.

● Wooden mold: Wooden mold manufacturing is relatively inexpensive and suitable for single-piece and small-batch production. Wood is relatively easy to obtain and has a low processing cost, it can adapt to complex design requirements. The casting surface is more smoother.

2. Casting bed annealing  

● Annealing treatment can significantly improve the internal structural stability of machine tool castings and prevent the occurrence of deformation and cracks. By eliminating internal stress, the toughness and service life of castings can be enhanced. In addition, annealing increases the toughness of the metal, improves the uniformity of the material structure, thereby reducing the risk of cracking and fracture.

● When Casting bed is finished annealing, It can be placed in an outdoor environment for a period of time, and naturally reduce its residual stress.

●If the casting is not annealed and aged, during its long-term use, the casting will deform due to the influence of internal stress, reducing the original accuracy of the CNC spinning machine.

3. Casting bed design

The distance between headstock and tailstock is longer, such as the Max blank diameter of the CNC spinning machine is 800mm, the Max spinning thickness is 3mm stainless steel, the distance is over 1000mm, so you had better to increase the thickness or strength of the structural weak area.

4. Cross slide table and Casting bed CNC milling

The main function of the machine bed and cross slide table is to install the lead screw, linear guide and bearings. Therefore, the precision control of the bed is very important. The dimensional accuracy and positional tolerance often need to be controlled within 0.02mm.The main requirements include flatness, straightness and roughness.

5. Headstock and tailstock CNC boring 

Headstock and tailstock is processed by CNC boring, it needs to control the diameter accuracy of the holes, the headstock hole is in coordination wither the spindle , the tailstock holes is in coordination with the hydraulic cylinder.

6. Which components can be purchased directly

Motor, CNC system, Spindle, hydraulic cylinder and hydraulic station, lead screw, bearings, guide rail, pulleys and belts are the basic and standard components that you can buy from the supplier. They you help and tell you right specification according to your requirement.

● The best brand of key components  

Motor and CNC system : Siemens, GSK, Frank

Guide rail and lead screw : HWIN

Bearings : NSK

7. Assembly requirements

① The guide rail parallelism accuracy

There are two guide rail in the X-axial or Z-axis, When assembling, one of the guide rail must be taken as the reference, and the accuracy of the other lead screw should be tested with a dial indicator. The value displayed on the indicator should not exceed 0.02mm per meter. This inspection method is called mutual reference.

② The parallelism accuracy between guide rail and lead screw

Using the mutual reference ways to inspect this accuracy, it is same with the guide rail parallelism accuracy inspection.

③ The perpendicularity of cross slide

The perpendicularirty of X-axis and Z-axis needs to control with +-0.01mm.

④ The parallelism accuracy between spindle center and Z-axis center

When you finished the machine bed and cross slide assembly, you will put the headstock and spindle on the machine bed, you need to control the parallelism accuracy with 0.02mm.

⑤ The coaxiality between spindle and clamp center  

When put the tailstock on the machine bed, you need to control the coaxiality between spindle and clamp with +-0.02mm.

8. How to quickly eliminate cumulative inaccuracy

① hand scraping

When there is a problem with the machining accuracy of the machine bed, the parts are usually made to meet the precision requirements by scraping. However, the scraping speed is not very fast. When the error exceeds 0.1mm, the scraping efficiency will become increasingly lower. The standard for scraping is generally that there are 25 contact points per inch of the part.

② Reprocessing on the CNC milling machine

When the machining error is relatively large, manual scraping cannot be used to fix the parts, and the problematic parts have to be sent for processing by CNC milling.

9. Cumulative error

The designer of a spinning machine usually selects a part to eliminate cumulative errors. Generally, simple and small-sized parts are chosen for reprocessing to achieve the purpose of eliminating cumulative errors.

10. How to adjust the coaxiality of spindle and clamp

In theoretical design, we can make the center of the spindle approximately 15mm higher than the center of clamp( tailstock ) in height. When processing errors occur and the cumulative errors are generated after assembly, we can adjust them by using height-increasing blocks.we grind off the height-increasing block, then we can adjust and control the concentricity.

This ways is very convenient, as the height increasing blocks size is little, It avoids the respair of the tailstock by CNC milling.