A sweep pattern is a type of pattern used in casting where a shaped board or metal plate is rotated around a fixed axis to form the mould cavity. It is commonly used to produce large, symmetrical castings such as pipes and bells.

**What is a sweep pattern in manufacturing process?**

Sweep Pattern in Manufacturing Process (Casting)

A sweep pattern is a type of pattern used in casting to produce large, simple, and axisymmetric shapes. Instead of a complete pattern, a shaped wooden or metal sweep is rotated around a central spindle to form the mould cavity accurately and economically.

1. Definition of Sweep Pattern

A sweep pattern is a special type of pattern used in sand casting in which a shaped wooden or metal board (called a sweep) is rotated about a fixed central axis to generate the required mould cavity.

👉 Instead of using a full 3D pattern, the mould cavity is formed by sweeping a profile.

2. Principle of Sweep Pattern

A vertical spindle or post is fixed at the centre of the mould
The sweep board, cut to the required cross-section of the casting, is attached to the spindle
Sand is rammed around the spindle
The sweep is rotated (swept) around the axis
Excess sand is removed, leaving the desired mould cavity

This method is ideal for axisymmetric or circular shapes.

3. Construction of a Sweep Pattern

A sweep pattern consists of:

Sweep Board
- Shaped like the cross-section of the casting
- Made of wood or metal
Central Spindle / Pivot
- Acts as axis of rotation
Base Plate
- Supports mould and spindle

4. Procedure (Step-by-Step)

Fix the spindle at the centre of moulding box
Ram moulding sand around the spindle
Attach sweep board to spindle
Rotate sweep through 360°
Remove excess sand to form cavity
Withdraw sweep and spindle carefully
Prepare mould for pouring

5. Applications of Sweep Pattern

Used for large, symmetrical castings, such as:

Large pipes
Chimney bases
Bells
Flywheels
Manhole covers
Turbine casings

Especially useful when quantity is small but size is large.

6. Advantages of Sweep Pattern

Low cost compared to full pattern
Ideal for large-sized castings
Simple construction
Saves time and material
Suitable for one-off or small-batch production

7. Limitations of Sweep Pattern

Applicable only to circular or axisymmetric shapes
Requires skilled labour
Lower dimensional accuracy
Time-consuming for complex profiles
Not suitable for mass production

8. Comparison: Sweep Pattern vs Solid Pattern

Aspect	Sweep Pattern	Solid Pattern
Shape	Circular / symmetrical	Any shape
Cost	Very low	High for large castings
Accuracy	Moderate	High
Production	Small quantity	Medium to large
Pattern type	Partial	Complete

9. Key points to Remember

Sweep pattern is not a full pattern
Produces mould cavity by rotation
Used when making a full pattern is uneconomical
Mostly used in large cast iron castings

10. Conclusion

A sweep pattern is a pattern used in sand casting where a shaped board is rotated about a central axis to generate the mould cavity for large, symmetrical castings.