Quality Rivets for CNC Machinery: A Guide to Selecting Optimal Fasteners(laser etched glass Sandra)
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What are Rivets?
A rivet is a mechanical fastener that consists of two main parts - a smooth cylindrical shaft and a head. During installation, the rivet is placed in a pre-drilled hole through the materials being joined. The tail end is then upset, or deformed, to form a second head, clamping the materials together. This creates a permanent mechanical joint.
Common Types of Rivets
There are three main categories of rivets available for CNC machinery:
Solid/Blind Rivets - These have a preformed head on one end and are driven through a prepunched or predrilled hole. The tail end is upset to form the second head. Installation only requires access to one side of the material.
Semi-Tubular Rivets - These have a partial hole in the shaft and are inserted into a prepunched or predrilled hole. Upsetting deforms the shaft to flow metal into the matching hole in the top material. Access to both sides during installation is required.
Tubular Rivets - These have a hole extending through the center of the shaft. Tubular rivets produce a flush surface on both sides of the joined material when properly set. They also require access to both sides.
Material Considerations
Rivets come in a range of materials that provide different strengths and corrosion resistance:
- Aluminum - Lightweight and corrosion resistant but lower shear and tensile strength. Good for softer materials.
- Steel - Strong and durable for heavy duty applications but prone to rusting. Zinc or ceramic coatings can help resist corrosion.
- Stainless Steel - Excellent corrosion resistance and good strength. More expensive but ideal for harsh conditions.
- Copper - Soft material that deforms easily. Used for non-structural electrical connections.
- Monel - Corrosion resistant nickel alloy good for marine and chemical environments.
- Titanium - Very strong but lightweight. Resists heat and corrosion. Costly but ideal for aerospace applications.
For most CNC machinery, aluminum or steel rivets offer the best combination of strength, durability and cost. Stainless steel or titanium may be preferred for specialized uses.
Rivet Sizes
The shaft diameter and length are important factors in rivet selection. Common shaft sizes range from 1/16 inch to 1/4 inch in diameter. Length depends on material thickness, grip range requirements and whether a flush surface is needed.
Using the optimal rivet size helps ensure proper deformation and a tight joint. Oversized rivets can split the surrounding material while undersized rivets may not adequately fasten parts together. Matching rivet size to hole diameter is critical.
Quality and Precision
Several factors determine the quality and precision of rivets for CNC applications:
- Dimensional consistency - Shaft and head dimensions should have minimal deviations from specifications.
- Concentricity - The rivet head should be precisely centered on the shaft. Eccentricity can cause uneven deformation.
- Surface defects - Scratches, dents and grit on the shaft can impact insertion and deformation.
- Head shape - Well-formed mushroom shaped heads with smooth finishes upset evenly. Irregular head shapes often result in poor set.
- Hardness - Rivets should be uniformly work hardened for proper deformation and shear strength.
- Grip range - The length needs to properly accommodate material thicknesses. Too short results in a loose joint while too long can crack the surrounding material.
Using precision engineered rivets helps avoid issues with flawed dimensions, off-center heads, blemishes or improper work hardening that could undermine performance. Consistent quality and accuracy are critical.
Rivet Certifications
Reputable rivet manufacturers will have their products certified to industry standards for quality assurance:
- ISO 9001 - Certifies quality management processes used in manufacturing.
- ASME B18.1 - Verifies rivet dimensional and manufacturing standards.
- MS/NASM 20426 - Aerospace grade certification for performance under extreme conditions.
- RoHS Compliant - Confirms rivets are free of hazardous substances.
Seeking rivets with certifications helps ensure you are getting products made to exacting standards ideal for CNC machinery.
Inspection and Testing
Thoroughly inspecting and testing rivets is advised to confirm they meet specifications and are fit for use in CNC processes. This should include:
- Visual inspection - Check for surface defects, proper head formation and shape, flash residue, and markings confirming size/material. Reject any with obvious flaws.
- Dimensional analysis - Sample rivets should be measured to verify shaft diameter, head thickness, and length are within tolerance.
- Hardness testing - Rockwell or Brinell testing will confirm proper work hardening and strength.
- Trial installation - Test riveting a sample piece to check set and grip range.
- Shear testing - Destructive shear tests determine the ultimate load to failure.
Verifying quality through inspection and testing provides further assurance you are getting optimal rivets for CNC machinery.
Proper rivet selection, inspection and testing helps ensure high precision and quality in CNC manufactured products. Consider shaft material and dimensions, head formation, dimensional consistency, material certifications, and thorough quality checks when sourcing rivets. Investing in the right rivets improves manufacturing operations and the durability of finished goods. With an understanding of rivet types and quality factors, manufacturers can confidently choose the best fastening solution for their CNC applications. CNC Milling CNC Machining