What Is The Main Advantage Of Broaching Over The Shaping Process?

What Is Broaching Process ？

Broaching is a machining method that removes material by using a tool with a series of gradually rising teeth. It Usually used to process inner surfaces with complex shapes, such as spline holes, gear tooth shapes, etc.

Advantages Of The Broaching Process

• High processing accuracy: high dimensional accuracy, shape accuracy, and good surface quality can be obtained.
• High production efficiency: One broaching stroke can complete the processing of complex shapes, suitable for mass production.
• High tool durability: The multi-tooth structure of the broach and reasonable cutting parameters ensure a long tool life.

Disadvantages Of The Broaching Process

• High cost of broaches: The design and manufacture of broaches are complex and expensive, and one type of broach can usually only process workpieces of one shape and size, so its versatility is poor.
• Complex machine tools: The structure of the broaching machine is relatively complex, making maintenance and adjustment difficult.
• Not suitable for processing blind holes and stepped holes: Due to the structural limitations of the broach, such shapes can not be processed.

Application of Broaching Process

• Automobile manufacturing industry: used for processing high-precision parts such as cylinder blocks of automobile engines, gear inner holes of transmissions, and splines.
  • For example, the processing of internal spline shaft holes in automobile transmissions.

• Aerospace field: manufacturing aircraft engine blade mortises, landing gear parts, etc.
  • Such as the processing of some high-precision holes and slots on aircraft landing gear.

• Machinery manufacturing industry: processing screws, worms and other parts of various machine tools.
  • For example, thread processing of high-precision screws.

What Is Shaping Process?

Shaping is the use of a planer blade to cut the workpiece in linear reciprocating motion. Mainly used for processing flat surfaces, dovetail grooves, T-shaped grooves, etc.

Advantages Of The Shaping Process

High cost of broaches: The design and manufacture of broaches are complex and expensive, and one type of broach can usually only process workpieces of one shape and size, so its versatility is poor.
Complex machine tools: The structure of the broaching machine is relatively complex, making maintenance and adjustment difficult.
Not suitable for processing blind holes and stepped holes: Due to the structural limitations of the broach, such shapes can not be processed.

Disadvantages Of The Shaping Process

• Low production efficiency: The reciprocating motion of the tool leads to the existence of empty stroke and the processing speed is slow.
• The machining accuracy is relatively low: Affected by the movement of the machine tool and tool, the accuracy and surface quality are not as good as broaching.
• High labor intensity: Operators need frequent manual operations, which results in high labor intensity.

Application of Shaping Process

• Mold making: Machining flat surfaces and simple shaped grooves of molds.
  • For example, the processing of flat parting surfaces of injection molds.

• Repair and small batch production: Repair damaged parts, or produce some simple-shaped parts in small batches.
  • For example, when repairing equipment, processing some replacement flat parts.

• Woodworking industry: used for processing flat surfaces, right-angled edges, etc. of wooden boards.
  • For example, processing logs into flat planks.

• General machining: processing machine tool guide rail planes, box planes, etc.
  • For example, surface processing of machine tool beds.

What Is The Difference Between Broaching And Shaping?

Broaching and Shaping are distinct machining operations. Their differences can be summarised as follows:

• Operational principle:
  • Broaching is a machining process that involves using a specialised tool called a broach to remove a thin layer of metal from a workpiece, one tooth at a time. This method allows for improved dimensional precision and reduced surface roughness. This is a highly effective approach of completing a task.
  • Shaping involves the use of a tool, such as a planer, to move back and forth in a straight line across the surface of the workpiece.

• Features being processed:
  • Broaching can be completed in a single working stroke. Typically, it exhibits excellent precision in processing and a low level of surface roughness. Nevertheless, the broaching tool possesses an intricate configuration, substantial manufacturing expenses, and a certain level of specialisation, making it primarily suitable for mass production.
  • Shaping exhibits comparatively lower processing efficiency and may not achieve the same level of accuracy and surface quality as broaching. However, planing offers a certain degree of adaptability and flexibility, along with relatively lower costs.

• Processing scope:
  • Broaching is capable of machining variously shaped through holes, such as spline holes and internal gears, as well as outside surfaces that are free from obstructions. However, it is not suitable for machining blind holes, deep holes, step holes, holes in thin-walled objects, and holes with obstructions. The external surface can be processed with shaping to create planes, grooves, and other features.

• Cutlery:
  • The broach used for broaching is a multi-tooth instrument with progressively larger teeth, while the planer used for shaping has a comparatively uncomplicated construction.

• Movement mode:
  • During broaching, the broach exhibits linear motion in relation to the workpiece, either with relative rotating motion.
  • In contrast, during shaping, the tool travels linearly in a back-and-forth motion.

• material removal method
  • The material removal method of broaching involves the sequential removal of material using teeth of increasing size on the broach.
  • On the other hand, shaping removes material in a step-by-step manner by the reciprocating action of the tool.

How To Choose A Suitable Processing Technology？

To choose the appropriate processing technology, whether to use Broaching or Shaping, you need to consider the following key factors:

• Workpiece shape and characteristics:
  • If the workpiece requires complex bore shapes, splines, or high-precision formed surfaces and can be designed into a shape suitable for broaching, then broaching may be a better choice. For example, internally splined shafts in automotive transmissions are often broached.
  • For simple straight shapes such as flat surfaces, grooves, dovetails, etc., planing may be more appropriate.

• Accuracy and surface quality requirements:
  • Broaching generally provides greater accuracy and better surface finish. If the accuracy and surface quality of the workpiece are extremely high, broaching may be preferable.
  • The precision and surface quality of planing are relatively low, but it can also meet the needs of some workpieces that do not have particularly demanding precision requirements.

• Production batch:
  • Broaching is suitable for high-volume production because the manufacturing cost of broaching tools is high, but the unit cost is low in high-volume production.
  • Planing offers greater flexibility and relatively low cost in small batch production.

• Material hardness and toughness:
  • For harder or tougher materials, broaching may be more suitable.
  • Planing may be easier on softer materials.

• Cost considerations:
  • Including tool costs, machine tool equipment costs, processing time costs, etc. Broaches are more expensive to manufacture and maintain, while planers generally have lower equipment costs.
  • If the production batch is large and precision requirements are high, although the initial investment in broaching is large, the cost may be lower in the long run; conversely, small batch production may be more economical in planing.

Existing equipment and technical capabilities of the factory:
If the factory already has suitable broaching or planing equipment and the operators are familiar with the corresponding process, they will tend to choose the existing process.

For example, a factory that mainly produces automobile engine parts may choose the broaching process for crankshaft bore splines that are mass-produced and require high precision; while for repair parts that occasionally need to be processed, such as simple flat spacers, they may use Planing process.

In short, when choosing between Broaching and Shaping, you need to comprehensively weigh the above factors and make the most appropriate decision based on specific production needs and conditions.