Tips & Tricks
Creating a perfect chamfer
Getting a perfect chamfer is not easy and in many cases people are not aware it can be done better. There are many variables that contribute to producing a good or bad chamfer. For example, grinding wheel speed, grinding wheel pressure, grinding wheel angle, and rotary table speed. With regards to grinding wheel angle, there are many different angles alone that affect your chamfer; for example, the approach angle, contact angle, contact point, and direction of wheel travel. When considering all of these things, getting the perfect chamfer can be a headache!
Typically when we are asked to visit a company who is having chamfering trouble, we encounter situations as pictured below; an inconsistent chamfer missing part of the lead side of the tooth, bouncing on the tip of the tooth, and heavy striations from an overly course wheel.
After our visit, we produce a chamfer that looks like the picture below and increases the wheel life.
To achieve the perfect chamfer, we will assume you have the basic setup correct and just need some tweaking. These are the basic fundamentals for a great chamfer:
Make sure that the grinding wheel engages the part extremely gently. If the grinding wheel engages the part too quickly then you will notice a burst of dust which could be three to four times as much material removed in that one instant as is removed when chamfering a single part. This burst may also produce a gouge in the part that can be noticeable to the eye.
Make sure that the grinding wheel produces an even spark pattern. Any interruption in the spark patter is efficiency loss. This loss - or interruption in the spark pattern - is the grinding wheel lifting and bouncing back down on the part. This can be subtle or extreme, but in any case, it creates a loss of wheel life and an inconsistent chamfer. You may notice the after-effect of this as a light and heavy chamfer on the lead and trail side of the gear tooth.
To eliminate the unsightly heavy chamfer marks, or what we call striations, you need to use a wheel that has natural shock-absorbing characteristics, such as the wheel we sell. Most companies end up using a rigid cutoff wheel, which is made of fiberglass reinforcing material bonded with a dense (usually black) open-cutting resin. Like many others, this is where we started. After much research and engineering we discovered an alternative. The wheel that should be used is a reinforced open-cutting, resin-bonded wheel that has some shock-absorbing properties. These wheels are typically lighter in color. The best way to see and feel the difference, if not in the performance alone, is to bounce the wheel against its cutting edge and the desk. The cutoff wheel will bounce instantly whereas our wheel will not bounce as much and will have more of a soft sound to it. Another way to check the difference between the wheels is to compare 1/16" thick wheels. The ideal wheel, such as the ones we sell, will flex slightly; the cutoff wheels will not flex, they will simply break.
When the three items above are addressed, the chamfering process will sound very different. It will not be a choppy snappy sound any longer; rather it will have a smooth sound to it. To the trained ear, it is possible to hear a good and bad chamfer from a distance without seeing it.
Following these steps will not only create a superior chamfer, it will also give you longer wheel life. For more information, wheel samples, or questions, please feel free to contact us.