Sand Blast Media: Perfecting Plastics

Sandblasting is a useful procedure in a wide range of applications and industries. It is used to clean, deburr, prepare for powder coating, derust, shot-peen, or remove paint from a surface. Sandblasting media can range from walnut shells to glass beads and tiny rock particulates.

Plastic blast media is a soft media used for many automotive and aerospace applications. It can remove paint and mould from delicate surfaces without causing damage. It is a less hazardous alternative to chemical stripping. Plastic blast media is made from 100% recycled materials and comes in five grades of hardness: Type I Polyester, Type II Urea, Type III Melamine, Type V Acrylic, and Type VI Clear-Cut.

Urea and Melamine plastic blasting media

Urea and Melamine blasting media are both used for paint stripping and removing coatings from steel or aluminium. They are also used for rubber mould cleaning, deflashing, deburring, and surface preparation.

Urea Type II is the most widely used plastic media. It is used for applications such as auto and aircraft restoration, delivering an efficient strip rate without damaging or warping the substrate surface. It is suitable for multiple substrates, including aircraft engine components, auto/bus/truck bodies, fiberglass components, printed circuit boards, and soft metals such as aluminium and magnesium. Urea has a Mohs hardness rating of 3.5, making it softer than Melamine.

Melamine Type III is the hardest of all plastic blast media, with a Mohs hardness rating of 4. It is used for applications that require a high strip rate without damaging the sub-surface. It is best used on steel or other very hard substrates, or when removing difficult surface contamination such as primer, paint, or scale. Melamine is more aggressive than Urea and is therefore used when more power is needed to remove tough coatings or contaminants.

Both Urea and Melamine blasting media are sold in 50-pound boxes or 250-pound drums.

Paint stripping

Sandblasting is a process that uses pressurised air to propel tiny particles, such as walnut shells, glass beads, or steel grit, at high speed to strip paint, smooth surfaces, or prepare them for painting. It is a common method for paint stripping, especially in the automotive, aerospace, and aviation industries.

When it comes to paint stripping, choosing the right blast media is crucial. For softer surfaces like wood, walnut shells or corn cobs are ideal as they are gentle and biodegradable. Glass beads are another option for achieving a smooth, bright finish without causing etching. They are recyclable and cost-effective, as they can be used up to 100 times.

For harder surfaces, aluminium oxide is a popular choice due to its sharpness and hardness. It is often used for paint removal, general cleaning, and glass etching. However, aluminium oxide may not be suitable for aluminium surfaces as it can cause corrosion.

Plastic media blasting is a preferred method for paint stripping in the automotive and aerospace industries. It is gentle on surfaces, removing paint without causing damage or leaving a residue. Plastic media can be reused and recycled, making it a cost-effective and environmentally friendly option. It also produces less dust, reducing potential health risks for workers.

Dustless blasting is another modern paint stripping method that is safe, effective, and eco-friendly. It uses a dustless blasting media and high-pressure air to remove paint without damaging the underlying surface. This process can be completed quickly and is versatile enough to be used indoors or outdoors.

Deflashing and deburring

There are several traditional methods of deflashing and deburring, including manual deburring, mechanical deburring, vibratory tumbling, cryogenic deflashing, and media blasting. Manual deburring is the most common type, as it allows for great flexibility and instant inspection, and it generates the best quality without stressing the material. However, it can be expensive to maintain staff for this process, and there is the possibility of human error. Mechanical deburring involves mechanically grinding or sanding the burr off a manufactured part, but this can be time-consuming and the quality of the finish is not guaranteed.

Cryogenic deflashing and deburring are considered more efficient and cost-effective methods. They are secondary processes that remove surface defects without changing critical part dimensions or surface finish. Both processes subject parts to very cold temperatures, making the part defects brittle and easy to remove using a special non-abrasive media. Cryogenic deflashing is for parts that are injection-moulded, while cryogenic deburring is used for parts that are machined, typically with CNC equipment. Cryogenic deflashing is especially useful for removing excess material from hard-to-reach areas and tough geometries. Cryogenic deburring is effective at removing machined burrs from blind holes, through holes, and other challenging geometries.

Another method is dry ice blasting, which maintains the geometries of the finished part without the negative side effects of alternative methods. It does not alter the finished product geometries, eliminates cross-contamination, effectively removes various types of flash and burr, reduces part finishing time and costs, and leads to consistent quality.

Aerospace applications

Plastic blast media is soft, making it perfect for removing paint from the surface of fiberglass parts. This is crucial for the aerospace industry, as fiberglass parts are commonly used in manufacturing. The use of plastic ensures that there is no etching or stripping of these essential components. It is also versatile, as it comes in various shapes, sizes, and hardness levels, catering to a wide range of applications.

One of the key advantages of plastic blast media is its ability to produce very low dust levels, contributing to a safer work environment and reduced cleanup time and costs. Additionally, it is environmentally friendly, recyclable, and reusable, making it a sustainable and cost-effective choice for the industry.

Plastic blast media is also preferred by aviation MROs (Maintenance, Repair, and Overhaul) as it is MIL-SPEC approved. This approval ensures quality, consistency, and safety, meeting strict military standards. It is non-toxic, non-hazardous, and non-reactive, minimising potential risks to personnel and the environment. This approval also helps MROs demonstrate compliance with regulations set by aviation authorities, such as the Federal Aviation Administration (FAA).

Automotive applications

Plastic is a soft media that can be used in many automotive applications. It is ideal for removing paint and mould from delicate surfaces without causing damage. This makes it a safer alternative to chemical stripping, which is more hazardous. Plastic media blasting is also the recommended method for stripping all Ford and General Motors vehicles.

Plastic media blasting is a process for the rapid, economic and safe removal of coatings from almost any surface without the use of toxic chemical strippers, sandblasting, or hand or mechanical abrasion methods. It is similar to sandblasting but instead uses softer, reusable plastic particles at low blasting pressures of 14-40 psi. At these pressures, plastic media can remove coatings without damaging the underlying substrates, including aluminium, fibreglass, and even plastics.

The plastic media fractures and breaks as it impacts the work surface, retaining its sharp cutting edges. This means that as the media breaks down, it maintains its paint-removing ability until the particles are practically dust. This dust can be safely disposed of in a landfill as the media is made from inert, non-toxic materials.

Plastic media blasting is also more cost-effective than other methods. While the initial setup cost is relatively high, the media can be reclaimed, cleaned, and reused. This makes the operating costs competitive.

It is important to note that equipment designed for sandblasting should not be used for plastic media blasting as it can damage the vehicle and pulverise the media.

Frequently asked questions