Case Studies

Aviation:

The problem
Aviation maintenance has long been a nightmare when it comes to paint removal and parts maintenance. As the actual outer skin of an aircraft is very delicate aluminum layered together and held in place by millions of aluminum rivets, many traditional cleaning and stripping techniques are not only to time consuming, they often cause tremendous damage to the structure and integrity of the outer skin and parts being cleaned. The millions of rivets holding the aluminum panels together create painfully long hours when paint stripping.

Many aviation parts have been anodised in a bid to strengthen the metal and also acts as a corrosion protection. There are great concerns about the removal of the anodised coating when cleaning or maintenance is carried out. If the anodised coating is removed, the parts become weaker and are in danger of structural failure under normal stress. Furthermore, corrosion increases dramatically by the removal of the coating.

The Substrate
The outer skin of a commercial or airliner is made of aluminum or a composite with interwoven conductive fibers which provides a path for electric lightning strikes. Outer skin may come with added magnesium alloys, copper or other composite metals.
There are numerous variations of the delicate outer skin within the industry as technology has advanced.

Previous Methods
Traditional methods such as chemical stripping, abrasive blasting, manual hand sanding and high pressure water blasting are all common within the industry. Each method comes with a myriad of downfalls and constraints.

Chemical stripping involves the highly toxic and often carcinogenic chemicals being brushed or sprayed onto the aeroplane after large areas need to be masked off from the chemical as it can eat away at rubbers, glass and outer stripping. Most of the chemicals are highly toxic, not environmentally friendly and hazardous to the user. Once the chemical is applied, it needs time to eat into the paint. Once ready, the chemical must be either scrapped off manually with scrapers scratching the delicate surface, or high pressure water blasted from the surface creating chemical toxic slurry. The use of large volumes of water is yet another downfall when major water restrictions apply worldwide. The millions of rivets make manual scraping a nightmare as the paint must be removed from each individual rivet. Once all paint has been removed, there remains other issue that must be considered. As chemicals are liquid of paste, they tend to seep into cracks and in between window and rubbers. If the has not been neutralized properly, it is possible for the chemical to keep eating at the rubbers, glass or outer stripping.

Abrasive Blasting has long been used as an alternative to chemical stripping. The actual word “Abrasive Blasting” causes unrest to many people within the aviation industry. The abrasive blasting technique creates heat causing the delicate outer skin to warp. This method also removes the good metal from the outer skin which aids the warping effect. As abrasive blasting removes metal, there are only a very minimal times an outer skin can be blasted before holes appear. Many planes have been simply written off or must be re- skinned after an abrasive blast. When it comes to aviation parts, the abrasive blasting method comes into further problems with not only the removal of metal but the removal of the all important anodised coating.

Further problems arise when crack detection and x-rays of the aviation parts are due for maintenance. The pressure, hardness and density of conventional abrasive blasting media, tends to peen over any cracks or imperfections that might need to be identified for reconditioning or fault finding purposes. If cracks and imperfections are not detected, this may cause a mechanical failure to the reconditioned parts or structural failure to aviation parts. Cracks, faults and imperfections need to be identified in order to fix the problem.
The hard abrasive also tends to clog into the cracks of structural parts and must be then picked out manually to remove the contaminant.

Manual hand sanding and scraping is still a method used today in tight corners and around rivets where machinery can not reach. This method makes for a very lengthy process and very costly.

THE SOLUTION

Soda Blasting:

Soda Blasting has become the solution to many industry problems such as downtime, environmental and OH&S problems. Soda Blasting easily eliminates the associated problems that face the current aviation industry. Soda Blasting uses blasting media that is 100% food grade, biodegradable, non toxic, non hazardous, non sparking, non flammable, biodegradable, water soluble, odourless, eliminates odours, non irritant to the eyes and skin, non corrosive and mould resistant.

The soda blasting process can easily be used on the delicate outer skin of an aeroplane with no worry of warping as this process does not remove metal. The added benefit to this is that the outer skin can be soda blasted many, many time creating no warping, holes or damage. Paint removal becomes a quick and cost effective process and makes light work around the millions of rivets, corners and hard to reach areas. As Soda Blasting can be done completely without water or very minimal water, the water restriction situation becomes non existent. If paint removal is done dry, cleanup is as easy as blowing the surface down or a quick wash as the baking soda is water soluble. Large quantities can be vacuumed up with a workshop vacuum cleaner.

Soda blasting causes no damage to rubbers, outer stripping and even glass so preparation time is dramatically reduced as no masking or very little masking is needed. Further more soda blasting causes no damage to bearing, seals, hydraulic hoses, electric hoses or valve and hinge systems.

The benefits don’t end there. Soda Blasting aviation parts becomes a very quick, effective and efficient process. The anodised parts can be soda blasted with no worries of coating removal be it anodised or galvanised. Crack Detection becomes a breeze with soda blasting as this process actually cleans out the cracks and does not peen over existing cracks and other methods do. If any baking soda remains inside the crack, it can be easily washed out with water due to the water soluble nature of the soda. The Soda Blasting process as a whole increases efficiency, decreases downtime and directly eliminate many hazards to the user all the one package.

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