composites sample repair

8/8/2019 Composites Sample Repair

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SAMPLE REPAIR # 1: Honeycomb Part Edge Filling

Objective:

To seal edge of sample using filler

Tools & Equipment:

1. Finish sample

2. Resin / Hardener

3. Microballons

4. Masking tape

5. Ice cream stick

6. Modified drill bit OR 2-3 inches long nails (to be bend at 1/16 inch length)

7. Drill gun (lf required)

S. Sand paper grade 80

Procedures:

1. Use a modify drill bit or modify long nails to remove honeycomb segment

2. Make sure the depth of removal is 3-10 mm or 1/16 inch in length from the tip

3. Use a drill gun or manual removing the honeycomb segment

4. Ensure all crushed cell and excess honeycomb is removed

5. Vacuum any excess or left honeycomb debris.

6. Mask off the surrounding area of the edge t ip using masking tape.

7. Mix the resin and microballon properly (Filler mix)


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8. Fill the core edged with mix filler and apply adequate pressure using ice cream stick to the

filling area to ensure resin fully fill the honeycomb space and to remove any trap air,

moisture or bubbles

9. Let the filler mixture to cure about 1 hour (ensure fully cure by hand)

10. Do finishing by trimming the excess filler using sand paper. Ensure exact dimension of

the finish sample when sanding.

11. Inspect sample


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SAMPLE REPAIR # 2: Potty Compound Filling (Undercut repair)

Objective:

To repair honeycomb sample using potty compound method

Tools & Equipment:

1. Finish sample

2. Approve potting compound and hardener

3. Masking tape

4. Ice cream stick

5. Steel ruler

6. Modify drill bit or 2-3 inches long nails (to be bend at 1/8 inch)

7. Drill gun

8. Grinder

9. Sandpaper grade 80 and 800

Procedures:

1. Simulate a hole damage on the finish sample using grinder

2. Ensure damage of; hole diameter < 0.5 inch; only affected 1st skin and core

3. Proceed with mild sanding at the edges of damage to remove pultrudedfibers (80 grid)

4. Insert the modify drill bit (using drill gun OR manual) inside the damage hole and remove

damage honeycomb at 1/8 inch in length

5. Ensure all crushed cell walls are removed from the damage hole

6. Vacuum any left material or debris from the core


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7. Mask off around the hole area using masking tape

8. Mix properly the potty compound (with hardener).

9. Ensure no contamination inside hole be fore filling the hole with potty compound

10. Apply adequate pressure using ice cream stick to ensure the potty compound fully fillthe hold and all air bubbles are removed

11. Let the potting compound cure for 1 hour (Ensure fully cure by hand)

12. Inspect sample

13. Proceed with finishing by using sand paper (800 and 320 grid or finer). Trim all excess

potty compounds on the sample surfaces.


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SAMPLE REPAIR # 3: Typical Honeycomb Repair

Objective:

To proceed with a typical repair (step cut)

Tools & Equipment:

1. Finish sample

2. Grinder (Remove damage)

3. Masking tape

4. Steel ruler

5. Fabric scissor

6. Marker pen

7. Fiberglass cloth (Length/Width : )

8. Honeycomb core (Length/Width: ); (Thickness: )

9. Resin and Hardener

10. Brush / Metal roller

11. Steel bowl/paper cup

12. Ice cream stick

13. Digital weight scale

14. Mask

15. Latex glove

16. Respirator

17. Sand paper

18. Knife (Core)

19. ALL vacuum bagging material that are available


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20. Cleaning solvent (MEK) + rags

21. Others

Procedures:

A. Surface preparation

- Remove damage area of 3 inch diameter on the finish sample by using grinder (Damage

will only effected 1st skin and core)

- Check the damage removal to ensure the dimension is within 3 inch diameter

- Ensure all crushed cell walls are removed from the damage hole

- Vacuum any left material or debris from the core

- Clean damage hole with MEK

B. Step cut surface preparation

- Mask off around the hole area using masking tape.

- The measurement of the exact diameter of masking tape area is by adding up 0.5 inch

length (both side) at every layer starting with the first 3 inch damage diameter and adding 1

inch length (both side) for the final layer (Masking tape is t o avoid over sanding)

- Cut the 1st step cut layer (masking tape layer) and begin sanding. Sanding should be done

in one direction only. Avoid over sanding by looking at the glossiness and orientation

changes of the plies while sanding. Clean the dust or r esidue and wipe with MEK.

- Continue to proceed for 2nd and 3rd step cut layer.


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C. Material preparation

- Cut 4 layers of fiberglass (refer to step cut dimension given) and 1 piece of honeycomb

core plus 2 layers of fiberglass with exactly 3 inch diameter (act as binding layer between

core and skin).

- Prepare resin mixture. Pour resin into steel bowl/paper cup. Mix according to mixing ratio

of resin: hardener, 2 :1 (or depending on the manufacturer spec.)

- Stir the mixture with ice cream stick until resin mixture dissolved uniformly.

- Prepare gel coat by using resin mixture and by adding microballonuntil the mixture

thickens

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