What are the precautions in the startup process of NC machining

NC machining is the most widely used machining method at present, and it is also the basic skill that every machining worker must master. After starting up, workpiece clamping, workpiece touch count, tool preparation and processing parameter setting, the start up processing link is entered. What problems should operators pay attention to in this link?

1. Tool and feed speed

Before executing each program, all tools must be carefully checked to ensure that they are consistent with the tools specified in the programming instructions. At the beginning of processing, the feed speed shall be adjusted to the minimum, and the method of single section execution, rapid positioning and tool dropping shall be adopted. Attention must be focused when feeding, and the hand shall be placed on the stop key. If any problem is found, it must be stopped immediately. During processing, pay attention to the moving direction of the tool to ensure safe feed, and then slowly increase the feed speed until it reaches a suitable value. At the same time, add coolant or cold air to the tool and workpiece to reduce the cutting temperature.

2. Precautions for rough machining

When rough machining the workpiece, the operator shall not be too far away from the control panel, so as to ensure that the machine can be shut down for inspection in case of any abnormal phenomenon. After roughening, pull the meter again to ensure that the workpiece is not loose. If any, the workpiece must be corrected and touched again. During the processing, the processing parameters shall be continuously optimized according to the processing conditions to achieve the best effect.

Since roughing is a very critical process, after processing, measure whether the main dimension values are consistent with the drawing requirements. After self inspection, it can be removed, and must be sent to the inspector for special inspection.

3. Precautions for drilling

The drilling process on the machining center is divided into three steps. First, the center drill must be used to locate the hole, then drill with a drill bit 0.5 to 2 mm smaller than the hole size in the drawing, and finally finish machining with a suitable drill bit.

4. Precautions for reaming

Similar to drilling, reaming the workpiece is also divided into three steps. First, use the center drill to locate the hole, then use a drill that is 0.5 to 3 mm smaller than the hole size in the drawing to drill, and finally use a reamer to ream the hole. During reaming, the spindle speed shall be controlled within 70 to 180 revolutions per minute, which shall neither be lower than the lower limit nor higher than the upper limit.

5. Precautions for boring

Boring of workpieces is divided into four steps. The first step is to use a central drill for positioning, the second step is to use a drill bit that is 1 to 2 mm smaller than the hole size in the drawing, the third step is to use a coarse boring cutter or milling cutter to process until there is only about 0.3 mm machining allowance left on one side, and the last step is to use a fine boring cutter with pre adjusted size for fine boring. The fine boring allowance shall not be less than 0.1 mm.

6. Precautions for direct NC operation

Before DNC numerical control processing, the workpiece shall be clamped, the zero position shall be set, and then the processing parameters shall be set. Open the processing program for data transfer processing in the computer to check, then let the computer enter the DNC state, and input the file name of the correct processing program. Next, press the “TAPE” key and the program start key on the machine tool, and the machine controller will display the flashing “LSK”. At this time, press Enter on the computer to perform DNC data transmission processing.