Short Answer:

Jigs and fixtures are made using strong and durable materials that can withstand cutting forces, vibrations, and repeated use during machining operations. The material should also be easy to machine, resist wear, and maintain shape under stress. Common materials include mild steel, cast iron, alloy steels, tool steels, aluminum, and sometimes non-metallic materials like plastics or composites for light-duty jobs.

The choice of material depends on factors like load, accuracy, cost, and machining type. Heavy-duty fixtures require tough metals, while lighter materials are used for low-force or temporary setups.

Detailed Explanation:

Materials used for making jigs and fixtures

In mechanical workshops and industries, jigs and fixtures are essential tools used to hold, locate, and guide the workpiece during machining operations like drilling, milling, turning, grinding, etc. Since they play a major role in maintaining accuracy, safety, and speed, it is important that they are made from suitable materials.

The material selected must offer high strength, wear resistance, dimensional stability, and should be easy to manufacture or machine. The working conditions such as cutting forces, tool vibration, and heat generation are also considered while selecting materials.

Let’s explore the most common materials used for making jigs and fixtures along with the reasons for their selection.

1. Mild Steel (MS)

Mild steel is the most widely used material for general-purpose jigs and fixtures. It is a low-carbon steel that is easy to cut, weld, and shape.

Reasons for use:

• Readily available and low cost
• Easy to machine and fabricate
• Good strength for medium-duty operations

Applications: Base plates, frames, bodies of simple jigs and fixtures

2. Cast Iron

Cast iron is used where rigidity and vibration damping are important. It is commonly used for fixture bases or heavy-duty setups.

Reasons for use:

• Excellent vibration absorption during cutting
• High compressive strength
• Stable and dimensionally accurate

Applications: Milling fixture bases, boring fixtures, inspection fixtures

3. Tool Steel

Tool steels are high-carbon, high-hardness materials used for wear-resistant parts of jigs and fixtures, especially where cutting or guiding tools are involved.

Reasons for use:

• Very hard and wear-resistant
• Retains shape under stress and heat
• Long life even in high-speed operations

Applications: Drill bushings, guide plates, dowel pins, locating components

4. Alloy Steel

Alloy steels are used when higher strength and toughness are required compared to mild steel.

Reasons for use:

• Stronger and more durable than MS
• Can be heat treated for added hardness
• Suitable for complex and high-load applications

Applications: Clamping arms, fixture blocks, support rods

5. Aluminum and Its Alloys

Aluminum is lightweight and corrosion-resistant. It is used for light-duty jigs and fixtures where heavy strength is not needed.

Reasons for use:

• Easy to machine and handle
• Reduces overall fixture weight
• Non-magnetic and corrosion-resistant

Applications: Electronic or aerospace fixtures, inspection jigs, soft material support

6. Non-Metallic Materials (Plastics, Composites, Nylon, etc.)

In some cases, non-metallic materials like nylon, PVC, bakelite, and fiberglass composites are used for soft or delicate operations.

Reasons for use:

• Lightweight and easy to fabricate
• Does not damage delicate parts
• Electrical insulation and corrosion resistance

Applications: PCB holding fixtures, light inspection jigs, soft component clamping

Factors affecting material selection

1. Type of operation (drilling, milling, grinding)
2. Force and load involved
3. Accuracy and wear resistance required
4. Machining and fabrication ease
5. Cost and availability of material
6. Expected life span of the jig or fixture

Conclusion

The materials used for making jigs and fixtures include mild steel, cast iron, tool steel, alloy steel, aluminum, and non-metallic materials like plastics. The selection depends on the nature of the job, required strength, accuracy, and cost. Using the right material ensures that the jig or fixture lasts longer, performs accurately, and improves overall machining efficiency. Choosing the correct material is a key step in good fixture and jig design.