Selection of bore dosage
⑴Bore
The bore tolerance is the remaining depth of cut for the bore. Usually the tolerance for bore is less than the tolerance for bore or bore. Too large a reaming tolerance will increase the cutting pressure and damage the reamer, resulting in a rough surface. StayWhen it is too large, the rough hinges and the thin hinges can be separated to ensure the technical requirements.
On the other hand, if the gross margin is too small, the reamer will wear prematurely, unable to cut normally, and the surface roughness will be poor. Generally, the bore tolerance is 0.1-0.25mm. For larger diameter holes, the tolerance cannot be greater than 0.3mm.
There is experience that recommends leaving a thickness of 1-3% of the reamer diameter as the reaming tolerance (diameter value). For example, it is more appropriate to add a Φ20 reamer to a hole diameter of approximately Φ19.6:20. -(20*2/ 100)=19.6 For hard materials and some aerospace materials, the tolerance bore is generally lower.
⑵Boring feed
The feed of boring is greater than that of drilling, generally 2 to 3 times. The purpose of setting a higher feed rate is to allow the reamer to cut the material instead of scrubbing the material. However, the Ra value of the bore hole roughness increases with increasing feed quantity. If the feed amount is too small, the radial friction will increase and the reamer will wear quickly, causing the reamer to vibrate and make the hole surface rough.
To process steel parts with a standard steel reamer, to obtain surface roughness Ra0.63, the feed rate cannot exceed 0.5 mm/r. For cast iron parts, it can be increased up to 0.85 mm/r.
⑶Spindle speed of boring operation
Various bore dosage factors have an impact on the surface roughness of the bore, among which reaming speed has the greatest impact. For example, if a steel reamer is used for reaming, a better roughness of Ra0.63;m is required for the middle. carbon steel parts stated that the reaming speed should not exceed 5m/min, because it is not easy to produce accumulated edges at that time, and the speed is not high when of the bore of cast iron, as the shavings are broken into granules; shapes, accumulated edges will not form, so the speed can be increased up to 8~10m/min. Usually, the spindle speed for boring can be selected as 2/3 of the spindle speed for drilling on the same material.
For example, if the drilling spindle speed is 500 rpm, then it is more reasonable to set the boring spindle speed to 2/3: 500*0.660=330 rpm
The so-called reamer is actually boring. Precision boring generally has a side margin of 0.03 to 0.1, a rotation speed of 300 to 1000, and a feed rate of 30 to 100, whichever is more suitable.
Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.
