Producing High Quality Rivets with CNC Machining(snap fit design guide Horace)
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Material Selection
The substrate material used for rivets heavily impacts strength, durability, corrosion resistance and other factors. CNC machining provides flexibility to manufacture rivets from various metals and alloys tailored to application needs. Common materials include aluminum, steel, stainless steel, titanium and specialty alloys like Inconel or Hastelloy. The material can be optimized to withstand shear loads, fatigue, impacts, temperature extremes and chemical exposure. CNC mills and lathes have automatic tool changers to efficiently machine different materials.
Precision Tolerances
Rivet dimensions must be held to tight tolerances for proper fit and function. A rivet hole that is too large or a rivet stem that is undersized can cause joint failure. CNC machines index rivet blanks precisely and use digital readouts to monitor dimensional accuracy during machining. Parts are machined within 0.005 inches or better of specifications. Repeatable precision ensures each rivet matches the design.
Automated Manufacturing
CNC equipment automates production by executing machining operations based on CAD/CAM programming. Once the machine is initially set up and programs are proven out, minimal operator intervention is needed. Automation increases throughput compared to manual methods. Lights-out manufacturing can further maximize productivity. The consistent automation produces uniform rivet quality. Random human errors from fatigue or inattention are eliminated.
Surface Finish
The surface finish of the rivet has implications for installation, corrosion resistance and aesthetics. CNC machines can control surface roughness and apply coatings for the appropriate finish. A smooth finish that minimizes friction may be preferred for rivets that will be installed by automatic riveting systems. An anti-galling treatment prevents material transfer between mating surfaces. Additional coatings such as zinc plating may be applied for corrosion protection. Adjustable coolant flow and precise toolpaths also prevent defects like chatter marks.
Head Styles
Rivets come in a range of head shapes like round, countersunk, flat and brazier. The head must match the parts being joined and installation tooling. CNC machining has the flexibility to produce any required rivet head style. The programs simply index the rivet blank and follow the appropriate toolpaths to cut the head profile. Quick change tooling further reduces changeover time between different head configurations.
Secondary Operations
Beyond basic rivet machining, CNC equipment can incorporate other secondary operations for improved quality and functionality:
- Threading - Threads may be rolled or machined into the rivet stem to facilitate assembly with nuts or threaded holes. The threads match application interface points.
- Grooving - Circular or longitudinal grooves add lubrication reservoirs, improve spin resistance or provide locking ability.
- Head texturing - Textured finishes like knurling deter loosening and strengthen grip for hand-driven rivets.
- Heat treatment - Post-machining heat treatment improves hardness, strength and other properties.
Quality Control
CNC processes enable in-process inspection and data collection to verify rivet quality. Probing checks dimensional conformance and tools monitor critical parameters. Statistical analysis highlights production trends. Products not meeting specifications are automatically flagged for removal. This prevents out-of-tolerance rivets from impacting downstream operations. Real-time feedback allows adjustments to keep machining consistent.
Rivet Design for CNC
To capitalize on CNC machining, rivets should be designed with manufacturability in mind. Inside corners and small radii should be avoided. Generous fillets and chamfers facilitate machining. Standard head dimensions match existing tooling. Allowances for coating thicknesses are incorporated into the design. Component geometries should also enable fixturing for secure machining access. Considering these factors when designing rivets results in higher manufacturability using CNC equipment.
In summary, CNC machining delivers tangible advantages for producing high quality rivets with precision, consistency and efficiency. The technology to accurately machine parts from metals and alloys makes it well-suited for rivet manufacturing. Automation increases throughput while the extensive process control ensures each rivet meets specifications. With capabilities to produce various head styles, materials, secondary features and more, CNC provides flexibility for rivets tailored to the application. By implementing CNC machining, manufacturers can meet demanding rivet quality standards for optimal fastening performance. CNC Milling CNC Machining