Date: 2024-03-12 20:55

BMW Info

ChatGPT

Paint

A35 - Monaco Blue Metallic.

Front Bumper specifications

Materials I buy and processes

Crack Fix

Without iron mesh

• We can just hit the surface and when is melted start adding the plastic

With iron mesh

This fix is more suitable for bumpers cracks

• In the back we place the iron mesh and hit it until it got in to the plastic
  • The surface covered could half inch to each side along the crack.
• We cover the fixed are with plastic
  • Sounds like the best option in this step is to apply Fiberflex because we are not looking for a symbiosis but more for a glue or plastic cover.
• In the front we made a route with a similar width as the stick PP we are planing to use but not too deep, then we can also can smooth the side of the route.
• We place the PP and hit it piece by piece until bumper and the PP becomes ones.
• In order to smooth the front we can again use Fiberflex or body filler.

Sand Papers

I bought Multi-Purpose (80, 120, 220), Waterproof (220, 320, 400)
And here is the recommended use:

• 80, 320 after body filler
• 400 with water after primer

Paint Supplies

R & E Paint Supply

• 3680031 - 2k primer
  • Remember to sand with 80 and 320 before apply
  • Clean with Paint Thinner
  • At least twice, chat GPT mentioned light coat
• BMW A35, Monaco Blue Metallic
  • Remember to wet sand with 400 before apply
  • Clean with a wet rag
  • At least twice, chat GPT mentioned light coat
• 3680061 - Clear coat

Body repair

Resin & hardener + Fiberglass Cloth

How to Repair a Cracked Bumper - YouTube

Steps:

• Sand body's back and crack borders.
• Align and tape hard so stay aligned.
• Apply the Resin & hardener + Fiberglass Cloth
• Sand the front and apply the Fiberglass Body Filler
• Sand and if we got new imperfections apply the regular Hardener
• Sand, apply the Primer,
  • Sand and apply the Paint Color], in the video was an spry and tree to four layers.
  • Apply the the Clear coat , again spry and two or three layers.

Materials

• Acetone to clean the plastic's surface before applying materials like epoxy glues or welding plastics
• Fiberglass Body Filler, could the right alternative for the front during the first layer of filler to to enforce the bond between the two pars broken/separated. This material needs the Hardener
• Body Filler, used for small parts apart of the crack. This material needs the Hardener
• Primer, applied before the Paint Color, can be in spry mode.
• Clear coat, last layer of material, applied to protect the paint.

Plastic Bonder & Microfiber Cloth

DIY Bumper Crack Repair - YouTube

Steps:

• Align and tape hard so stay aligned.
• Sand and apply a layer of the Plastic Bonder, then pieces of Microfiber Cloth along the crack and another layer of the Plastic Bonder.
• The front process is pretty similar to the process above.
  In this video was used Primer, Paint Color and Clear coat in the spry form, same as in the video above.

Materials

• Paint Thinner, same as Acetone and Alcohol , used to clean the plastic surfaces.
• Plastic Bonder, JB weld Plastic Bonder

FiberFlex, hot-melt adhesive

(94) FiberFlex Bumper Repair - YouTube

This doesn't looks the right fix for my bumper but for flexible bumper, for mine seem to be more suitable to PP plastics,

Type of plastics

How to Identify Any Type of Plastic | Orange Plastics Academy - YouTube

| Name & melting point | Low Density (Floating) | Compression Resistence | Burn |
| ------------------------------------------------------------------------------------------------------------------- | --- | --- | ---------------------- | ---------------------- | -------------------------------------------------------- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Polyethylene (PE)
- LDPE around 105°C to 115°C (221°F to 239°F)
- HDPE around 120°C to 130°C (248°F to 266°F) | YES | Bending Family | Light Yellow flames with Blue Core
Candle-like effect |
| Polypropylene (PP)
- 130°C to 171°C (266°F to 340°F) | YES | Bending Family | Light Yellow flames with Blue Core
Oil-like substance |
| Acrylonitrile butadiene styrene (ABS)
- 105°C to 125°C (221°F to 257°F) | NO | Breakable Family | Thick Smoke Styrine Smell |
| Polyamide (PA)
- Nylon 6: 220°C to 225°C (428°F to 437°F).
- Nylon 6,6: 260°C to 265°C (500°F to 509°F). | NO | Bending Family | Blue flames with Yellow layer
Wool-like |
| Polycarbonate (PC)
- 225°C to 300°C (437°F to 572°F) | NO | Bending Family | Puffs pf smoke
Sweet scent |
| Polyoxymethylene (POM)
- 165°C to 185°C (329°F to 365°F) | NO | Memory Form | Invisible flame
Formaldehide scent |
| Polyethylene terephathalate (PET)
- 250°C to 260°C (482°F to 500°F) | NO | Don't know | Yellow flame with and Smokey
Sweet scent |

• Bumper, ChatGPT said that is PP.
• Bumper I found has a kind of blue flame and yellow at the top we can think is a PP but since it doesn't float we should go for PA.
• Bumper Accessories, ChatGPT says that is likely PP or PA and since in the plastic didn't pass the floating test sounds like is PA, the only problem is that it didn't have flame as the PA above.

Store

If in Amazon doesn't have the Plastic Welding Rods this page Polyvance - We help people repair plastic is an option, we should go to the bottom, under All products, to the list of Plastic Welding Rods and there is a list will all the types of Plastic Welding Rods in existence.

Paiting / Finish

Need to be check if is needed a another layer of something before on top of th

Light Coats (Primer and Base Coat):

• Distance: Hold the spray can about 6 to 8 inches away from the surface. This distance allows for a wide enough spray pattern to cover the surface evenly without causing runs.
• Speed: Move the can at a steady pace that allows you to cover the area with a thin, even layer of paint. The goal is to mist the surface lightly, not saturate it.
• Pattern: Use a consistent, overlapping pattern, such as side-to-side or up-and-down movements. Begin spraying before you reach the surface and continue spraying past the end of the area to ensure even coverage and prevent buildup at the edges.
• Overlap: Each pass should overlap the previous one by about 50% to ensure uniform coverage without heavy buildup.

Regular Coats (Clear Coat):

• Distance: The same general distance of 6 to 8 inches applies. However, you may slightly adjust based on the spray can's instructions and the viscosity of the clear coat.
• Speed: Move the can slightly slower than when applying light coats. This allows for a wetter application, which is necessary for the clear coat to flow out and level properly, creating a smooth, glossy finish.
• Pattern and Overlap: Similar to light coats, maintain a consistent pattern with 50% overlap. The key difference is in the application's thickness; you're aiming for a coat that's wet enough to level out but not so heavy that it runs or sags.

General Tips for Both:

• Shake the Can Well: Before spraying, shake the can for the amount of time recommended by the manufacturer to ensure the paint is well mixed.
• Test Spray: Always do a test spray on a piece of cardboard or scrap material to check the spray pattern and adjust your technique as needed.
• Environment: Apply paint in a well-ventilated area, and avoid painting in extreme temperatures or high humidity to ensure the paint dries and cures properly.

Conclusion:

The technique involves a combination of maintaining the correct distance, adjusting your movement speed, and employing a consistent spray pattern with appropriate overlap. While the principles are similar for both light and regular coats, the key difference lies in the thickness of the application and the speed of movement, with light coats being thinner and applied more quickly, and regular coats applied slower to achieve a wetter finish.

Parts materials

Lower Lights Holder

Is PBT GF30 (Polybutylene Terephthalate reinforced with 30% glass fibers) and seem like the better welding rod will be the one made of PC between my optons.

However, in the absence of a PBT-specific welding rod, the closest alternative from your list based on compatibility with thermoplastic engineering polymers might be PC (Polycarbonate) rods. PC shares some characteristics with PBT, such as good heat resistance and mechanical strength. While not ideal, PC could be the most suitable option in a pinch, but it's important to note that the weld's strength, durability, and thermal characteristics may not perfectly match the original PBT GF30 material.

For the best results, it's recommended to use a welding rod made from the same material as the piece being repaired (PBT GF30 in this case). If you choose to proceed with an alternative like PC, consider conducting a test weld on a non-critical area or scrap piece of similar material to assess compatibility and strength before proceeding with the actual repair.

Front Bumper Grid

Seems like is a type of PP so the better welding rod option will be also the one made of PP

The unclear letters between "PP" and "D" might further specify the plastic grade or additional modifications, but without being able to decipher these letters, it's challenging to determine their exact meaning.

In the context of plastic welding or repairs, identifying that the base material is polypropylene (PP) is crucial. For repairing a bumper with this composition, you would ideally use a PP welding rod to ensure the best compatibility and bond strength. The additional modifiers (indicated by "M+TV20") suggest that the material has specific enhancements for durability or other properties, which should be considered if you're aiming for a repair that closely matches the original material's performance.