23-07-2012, 11:12 AM
DESIGN CONSIDERATIONS FOR AN ASSEMBLY JIG
DESIGN CONSIDERATIONS FOR AN ASSEMBLY JIG.ppt (Size: 320 KB / Downloads: 58)
Check for pre manufacture designs
Standard stock sizes and standard tooling elements
In-house machining capability
Skilled / unskilled operator
Intended use – Machining / Assembly / Stage process / Inspection
Location facility and accuracy
Tolerances to be maintained
Adequate Clamping facility
Built in checking facility
Simple to manufacture and use
Part removal / chip and coolant removal
Access for cutting tools / operations
Slip bushings where multiple operations are intended
Eliminate loose pieces
Provision of pneumatic / hydraulic lines
DESIGN FEATURES OF ASSEMBLY JIGS
Locate and securely hold components and assemblies in the proper 3-D relationship w.r.t each other during the assembly operations.
Ensure repeatability and interchangability can be achieved.
Control over contours and profiles of components.
Provide convenient access and ease of working during assembly operations (ergonomics).
Provide safety for personnel working on the jigs/fixtures.
When required, serve as acceptance gaugesfor finished components.
TYPES OF LOCATORS –
ICY locators
Tooling hole locators
Contour locators
Butting contour plates
Check contour plates
Locators for other system brackets
TOOLING APPROACH - AIRCRAFT ASSEMBLY
ASSEMBLY JIG PREPARATION
Calibration of jig locators and verification of ICY locators using MTG/Gauges
Inspection certification and proving
TYPICAL ASSEMBLY SEQUENCE
Fittings at ICY points are first located on the jig
Then machined parts which are more rigid and accurate
Finally sheet metal parts are loaded on the jig
Pilot holes are marked and drilled
Pilot holes are transferred to skin
Skin is trimmed and suited to NMG
Contour is verified using templates before final rivetting
Final rivetting and sealant application
Presentation for final inspection
Unloading of assembly/sub-assembly
INTERCHANGEABILITY
Interchangeability can be broadly classified as :
EXTERNAL INTERCHANGABILITY
Interchangeability between complete airframe structure and other parts/assemblies not controlled by the airframe manufacturer.
Eg.: Engine, Ejection seats, Landing gear, Instruments, Guns etc.
INTERNAL INTERCHANABILITY
Interchangeability within the airframe structure and its components.
Eg. : Wings, Access panel, Aileron, Control surfaces etc.