Selection of Reaming Amount
⑴ Reaming allowance The reaming allowance is the depth of cut reserved for reaming. Usually, the allowance for reaming is smaller than the allowance for reaming or boring. Too much reaming allowance will increase the cutting pressure and damage the reamer, resulting in roughness of the processed surface. When the margin is too large, the rough hinge and the fine hinge can be separated to ensure the technical requirements.
On the other hand, if the billet allowance is too small, the reamer will wear out prematurely and cannot be cut normally, and the surface roughness will also be poor. Generally, the reaming allowance is 0.1~0.25mm, and for larger diameter holes, the allowance cannot be greater than 0.3mm.
There is an experience that suggests to reserve a thickness of 1~3% of the reamer diameter as the reaming allowance (diameter value). For example, it is more appropriate to add a Φ20 reamer with a hole diameter of about Φ19.6: 20-(20*2/ 100)=19.6 Reaming allowances are usually made smaller for hard materials and some aerospace materials.
(2) Feed rate of reaming The feed rate of reaming is larger than that of drilling, usually 2~3 times of it. The purpose of the higher feed rate is to make the reamer cut the material instead of the abrasive material. However, the roughness Ra value of reaming increases with the increase of feed rate. If the feed rate is too small, the radial friction will increase, and the reamer will wear out rapidly, causing the reamer to vibrate and roughen the surface of the hole.
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Standard steel reamer processing steel parts, to obtain surface roughness Ra0.63, the feed rate should not exceed 0.5mm/r, for cast iron parts, it can be increased to 0.85mm/r.
⑶ Reaming spindle speed and reaming amount All elements have an impact on the surface roughness of the reaming hole, among which the reaming speed has the greatest influence. If a steel reamer is used for reaming, a better roughness Ra0.63; m , For medium carbon steel workpieces, the reaming speed should not exceed 5m/min, because built-up edge is not easy to occur at this time, and the speed is not high; when reaming cast iron, because the chips are broken into granular, no accumulated edge will be formed. Edges, so the speed can be increased to 8~10m/min. Generally, the spindle speed of reaming can be selected as 2/3 of the spindle speed of drilling on the same material.
For example, if the drilling spindle speed is 500r/min, it is more reasonable to set the reaming spindle speed at 2/3 of it: 500*0.660=330r/min
The so-called reamer is actually boring. Fine boring usually has a unilateral margin of 0.03-0.1 and a speed of 300-1000. The feed rate is between 30-100, depending on whether it is called a knife.
Post time: Aug-24-2023
