Table of Contents
At what condition positive rake angle is preferred?
Table: Differences between positive rake and negative rake
| Positive Rake Angle | Negative Rake Angle |
|---|---|
| Rake angle is considered as positive when sum of wedge angle and flank angle is less than 90°. | Rake angle is considered as negative when sum of wedge angle and flank angle is greater than 90°. |
How does positive rake enhance the cutting operation?
Rake angle is a cutting edge angle that has large effects on cutting resistance, chip disposal, cutting temperature and tool life. Increasing rake angle in the positive (+) direction improves sharpness. Increasing rake angle by 1° in the positive (+) direction decreases cutting power by about 1\%.
What are the advantage of positive zero and negative rake angles?
A positive rake makes the tool tip less strong by reducing wedge angle; while, a negative rake overcomes this lacuna but increases the cutting power consumption because of higher shear deformation.
Why negative rake angle is used in brittle and hard tools?
To sustain under higher cutting force for longer duration, rake angle of the cutting tool is made negative taking advantage of stronger wedge. This, in turn, extends the tool life.
Why positive rake angle is provided?
Positive rake angles generally: Make the tool more sharp and pointed. This reduces the strength of the tool, as the small included angle in the tip may cause it to chip away. Reduce cutting forces and power requirements.
What is the advantage of positive rake angle?
What is the purpose of a rake angle?
Rake angle is cutting edge angle that has a large effect on cutting resistance, chip disposal, cutting temperature and tool life.
What is the difference between positive and negative rake angle?
The positive rake angle cause the face of the cutting tool to slant downward when moving away from the cutting edges. The negative rake angle cause this surface to slant upward when moving away from the cutting edge.
What is importance of rake?
A rake (Old English raca, cognate with Dutch hark, German Rechen, from the root meaning “to scrape together”, “heap up”) is a broom for outside use; a horticultural implement consisting of a toothed bar fixed transversely to a handle, or tines fixed to a handle, and used to collect leaves, hay, grass, etc., and in …
What is the advantage of a positive rake angle?
Positive rake angle makes the tool sharp and pointed, but reduce the strength of cutting edge. It helps the formation of continues chip in ductile material and contributes to avoiding the formation of build-up edge chip. HSS tools are typically given a positive rake angle. They used in machining of low-strength ferrous…
What is the rake angle of a cutting tool?
Rake angle may have positive, negative or even zero value, as elaborated in the following section. This value determines cutting force and power requirement, life of the cutting tool, chip deviation, etc. Rake angle also indirectly affects machinability.
What are the advantages of using a zero rake cutting tool?
Cutting tool with zero rake angle is easy to design and manufacture. Such tools also provide advantage while re-sharpening the tools. Thread cutting tools are usually provided with zero rake angle.
Why do we generally provide a negative rack angle to carbide tools?
We generally provide a negative rack angle to the carbide tools so that it can resist the higher cutting force. Due to the thicker cutting edge, the strength of this type of tool is more. Tool life is increased. The power required for the cut is more as the negative rake angle makes the tool blunt.