Chapter 7: Advanced Composite Material - FAA

Page 49

CSR 90433

A REF

100° ± 1°

B REF

C1 DIA

C2 DIA

D DIA

1/8 (–4)

0.028

0.028

0.195 0.189

0.195 0.189

0.132 0.129

5/32 (–5)

0.037

0.037

0.247 0.242

0.247 0.242

0.162 0.159

0.046

0.302 0.297

0.302 0.297

0.195 0.191

0.046

0.328 0.323

0.328 0.323

0.227 0.224

3/16 (–6) 7/32 (–7)

0.046 0.046

Hollow End E-Z Buck® Nominal Diameter

A (ref) for manufactured head B (ref) for shop-formed head

C2 Grip range

Rivet Diameter

D C1

100° ± 2°

Squeezer yoke or riveting machine

Upset Load (Lb) + 200 Lb

Cherry snap die (optional)

(839B3 = 3/16" shank size) (839B13 = 1/4" shank size) Note: 1 die fits all fastener diameters.

1/8" (–4)

2,500

5/32" (–5)

2,700

3/16" (–6)

3,000

Hollow End E-Z Buck®

7/32" (–7)

3,750

Composite material Cherry flaring snap die

Head dimple

Cherry Flaring Snap Die Part Numbers Rivet Diameter

3/16" Diameter Mount

1/4" Diameter Mount

1/8"

839B1-4

839B10-4

5/32"

839B1-5

839B10-5

3/16"

839B1-6

839B10-6

7/32"

839B1-7

839B10-7

Flushness +0.005 −0.000 Flushness +0.015 −0.000

Manufactured head

Shop formed head

Figure 7-82. Cherry’s E-Z buck hollow rivet.

Machining Processes and Equipment

Drilling Hole drilling in composite materials is different from drilling holes in metal aircraft structures. Different types of drill bits, higher speeds, and lower feeds are required to drill precision holes. Structures made from carbon fiber and epoxy resin are very hard and abrasive, requiring special flat flute drills or similar four-flute drills. Aramid fiber (Kevlar®)/epoxy composites are not as hard as carbon but are difficult to drill unless special cutters are used because the fibers tend to fray or shred unless they are cut clean while embedded in the epoxy. Special drill bits with clothes pin points and fish-tail points have been developed that slice the fibers prior to pulling them out of the drilled hole. If the Kevlar®/epoxy part is sandwiched between two metal parts, standard twist drills can be used.

Equipment Air-driven tools are used for drilling holes in composite materials. Drill motors with free speed of up to 20,000 rpm are used. A general rule for drilling composites is to use high speed and a low feed rate (pressure). Drilling equipment with a power feed control produces better hole quality than drill motors without power feed control. Drill guides are recommended, especially for thicker laminates. Do not use standard twist drill bits for drilling composite structures. Standard high-speed steel is unacceptable, because it dulls immediately, generates excessive heat, and causes ply delamination, fiber tear-out, and unacceptable hole quality. Drill bits used for carbon fiber and fiberglass are made from diamond-coated material or solid carbide because the fibers

7-49


Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.