Uses for Rivets in CNC Machining Processes(centrifugal casting Webb)

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Rivets are a fundamental hardware component utilized in many manufacturing and construction applications. While other fasteners like screws and bolts use threads to hold materials together, rivets employ a head and shank that is flared out to create a solid joint. The riveting process mechanically joins and locks materials by deforming the rivet and pressing a formed head into the material. Rivets come in several styles, sizes and materials for diverse functions.
In computer numerical control (CNC) machining, rivets serve important purposes in fixture design and metal fabrication. Understanding the capabilities of riveting allows CNC programmers and machine operators to produce high-quality parts efficiently. This article explores common uses for rivets in CNC machining operations.
One of the most frequent uses of rivets in CNC processes is fixturing. Fixtures firmly secure raw workpieces and set them in specific positions so the machine can precisely cut, drill and shape the material. Rivets assemble fixture components like riser blocks, clamps, stops and other parts to provide an interface between the workpiece and machine. The rivets act as fastening points to hold fixture sections in accurate alignment.
Rivets permit quick and reconfigurable fastening during the fixture building stage. Operators can dismantle and rearrange fixtures for new jobs more easily compared to welded fixtures. Common fixture rivets include blind rivets, tubular rivets and drive rivets. Blind rivets insert through holes in fixture materials from one side and buck outward on the backside. Tubular rivets flare into a funnel shape after insertion through coaligned holes. Drive rivets get driven into undersized holes to create tight fits.
Sheet Metal Fabrication
Riveting excels as a rapid joining technique for sheet metal fabrication. CNC punching centers and machining centers equipped with riveting tools can drill holes and drive rivets to assemble sheet metal components. Riveted sheet metal parts see widespread use in sectors like aerospace, automotive, electronics and construction.
Some advantages of CNC riveting for sheet metal include:
- High speed automated riveting drives down assembly times versus manual methods.
- Consistent quality since CNC machines regulate rivet placement and installation force.
- Ability to rivet thick and thin gauge sheets.
- Low-cost rivets compared to other fasteners.
- Rivets allow movement between sheets to accommodate thermal expansion.
Common sheet metal rivet types are solid rivets, blind rivets and self-piercing rivets. Solid rivets work for joining thicker sheets where access to both sides is available. Blind rivets insert from one side but flare on the backside. Self-piercing rivets cut through stacked sheets while flaring to interlock layers.
Joining Dissimilar Materials
Rivets present a practical technique for mechanically fastening dissimilar metals and other materials. The deformation of the rivet shank creates a clamping force to join different metals securely despite their variance in thermal expansion. This helps avoid cracking and warping problems seen with welded joints between dissimilar metals.
Some key applications include:
- Joining steel and aluminum components in aircraft assemblies.
- Attaching aluminum heat sinks to steel equipment housings.
- Joining insulation or plastic panels to metal framing studs.
- Securing plastic components to metal machine housings.
The choice of rivet material and style depends on the material characteristics. Softer or lower-strength materials often use blind or self-piercing rivets. Harder materials such as higher-strength steels may require more specialized rivets. Proper material selection prevents excessive material deformation during rivet setting.
Riveted Repairs
Riveted repairs serve as a practical field technique for fixing or reinforcing worn CNC machined parts. Technicians can rivet reinforcement plates over damaged or cracked areas to restore strength. Riveting also offers a quick structural repair if a part becomes warped or distorted over time. For equipment with riveted construction, replacing worn rivets with new ones also makes good fix.
The main advantage of rivet repair is that it avoids scrap and the high costs of re-machining replacement parts. Riveted patches let technicians extend equipment life at minimal cost. Portability of riveting tools allows repairs directly in the field rather than disassembling equipment for shop repairs. Overall, riveted repairs provide fast, economical solutions for maintaining high machine availability and lifecycles.
Design Considerations for CNC Riveting
To leverage rivets effectively in CNC applications, programmers and machinists should factor in key considerations:
- Joint Design - Allow proper edge distances, pitch distances and clearance for tool access. Avoid overlapping rivets.
- Sheet and Rivet Ductility - Pick rivet material that deformation matches the sheet. Dissimilar ductility risks cracked sheets or loose rivets.
- Rivet Strength - Size rivets to withstand shear, tensile and vibration loads. Meet safety factors for critical joints.
- Hole Fit - Hole diameter should match rivet size. Tight fits enhance strength while loose fits cause instability.
- Installation Method - Specify proper tools and force range for optimum rivet setting. Control impacts.
- Inspection - Visually inspect for proper rivet head formation, tight joints, and no cracks. Confirm strength meets specifications.
By selecting suitable rivets and integrating riveting steps into CNC programs, manufacturers can reap benefits like faster production, lower assembly costs, and high reliability across many applications.
Rivets continue to serve as a versatile fastening solution in today's CNC machining and fabrication operations. Their quick installation, joint strength, and low cost advantage make rivets ideal for production fixtures, sheet metal fabrication, dissimilar material joining, and field repairs. By understanding critical factors like joint design, material compatibility, and proper rivet setting technique, CNC programmers can effectively apply rivets to cut costs and improve manufacturing productivity. CNC Milling