Broaching is a machining process that uses a toothed tool called a broach to remove material from a workpiece to produce holes, slots and shapes in the workpiece. Broaching is commonly used to produce precision linear and angular surfaces with straight or irregular profiles as well as internal or external surfaces on mass-produced metal workpieces.
Types of Hand Tools
There are different types of broaches used depending on the shape that needs to be cut. Some common broach types include:
- Straight broaches: Used to cut straight slots and shapes without any angularity. These have straight rows of teeth.
- Angle broaches: Used to cut slots and shapes that involve angular cutting. The teeth are arranged at predetermined angles.
- Circular broaches: Used to cut circular, ring shaped or circular profiles. The teeth arrangement forms concentric circles.
- Form broaches: Used to cut complex profiles or shapes that cannot be produced using straight, angle or circular broaches. The teeth shape and arrangement matches the required profile.
Broaching Process
The basic Hand Tools process involves the following steps:
1. The workpiece is securely clamped using fixtures to prevent any movement during broaching operation. Proper clamping is critical for dimensional accuracy.
2. A lubricant is applied to reduce friction and heat generated during metal removal. Water-soluble cutting oils are commonly used.
The broach tool is positioned at the start point of the cut on the workpiece. It may be manually or automatically fed.
Using downward pressure, the broach is fed through the workpiece while the teeth shear off slices of metal in the required shape or profile.
The broaching strokes continue till the full shape is cut. Multiple passes may be required for deep cuts.
The broached workpiece is then unclamped and inspected for dimensional accuracy and surface finish.
Advantages of Broaching
Some of the key advantages of broaching include:
- High productivity: Broaching allows high volumes of precision workpieces to be produced quickly at a low unit cost. Complex profiles can be cut in a single pass.
- Accuracy: When properly applied, broaching can give very high dimensional accuracy of ±0.0025 mm or better. Close tolerances can be maintained in mass production.
- Surface finish: Broaching provides a smooth surface finish in the range of 0.8-1.6 μm Ra. No secondary finishing is usually needed.
- Reliability: Broaches have a long tool life and can produce thousands of accurately machined parts before requiring sharpening or replacement. This makes the process highly reliable for volume production.
- Applicable materials: Broaching can be used on a wide range of materials including steel, aluminum, copper, brass and plastics. Heat treated and hard metals can also be broached.
Design Considerations for Broaching
For successful broaching, careful broach and workpiece design is required. Some key factors to consider:
- Broach design: The broach tooth shape, spacing, set, clearance and arrangement need to match the required cut profile. Multiple-start teeth increase tool life.
- Workpiece material: The workpiece material hardness and machinability affects broach tool life and material removal rate.
- Clamping: Rigid clamping of the workpiece is needed to avoid distortion during machining.
- Cut depth: Incremental depth cuts may be needed for deep cuts to avoid tool breakage or workpiece damage. Shallow cuts increase tool life.
- Cutting speed: Lower speeds around 2-5 m/min are generally used, depending on material and tooth geometry. Faster speeds increase tool wear.
- Surface finish: Different broach tooth profiles and honing after broaching help obtain the desired surface roughness.
- Tolerances: Tool and workpiece tolerances need to be considered to achieve the required dimensional accuracy of cuts.
Quality Control in Broaching
For broaching to consistently deliver precision parts, quality control at different stages is important:
- Dimensional inspection: Random sampling checks that broached dimensions meet engineering specs. Precision measuring tools are used.
- Surface inspection: Surface roughness and finish are checked using surface profilers or comparators.
- Tool inspection: Broach teeth wear is monitored and tools are replaced once worn beyond limits. Tooth chipping can also reduce accuracy.
- Process parameters: Cutting speed, pressure, lubrication etc. are periodically measured to maintain consistent cutting conditions.
- Workholding fixtures: Fixture and clamping accuracy and repeatability is audited to avoid workpiece distortion.
- Machine maintenance: Periodic servicing keeps machines running accurately for long term production runs.
Broaching offers many advantages for precision shaping of workpieces. With proper process planning, tool and machine design, and quality control, it remains an indispensable high production machining technique in industries like automotive, aerospace and fastener manufacturing. Its ability to deliver close tolerances in high volumes makes broaching T an essential manufacturing process.
Get more insights on- Hand Tools
Explore More Related Article On- Customer Relationship Management Market
For Deeper Insights, Find the Report in the Language that You want.
About Author:
Money Singh is a seasoned content writer with over four years of experience in the market research sector. Her expertise spans various industries, including food and beverages, biotechnology, chemical and materials, defense and aerospace, consumer goods, etc. (https://www.linkedin.com/in/money-singh-590844163)