External Structure Materials & Durability

The types of materials used to construct the external structure and internal parts of a vacuum cleaner play a major role in the length of its life span as well as the extent of its maintenance expenses. Typically, vacuum cleaners are made of a combination of metals and various plastics. With the development of the Plastics Industry, many parts which were once metal are now made of much lighter and often stronger plastics. While reducing the production costs considerably, this change over has also made vacuum cleaners much lighter and easier to use. The key to durability is often in the excellence of design as well as the types of plastics used for various parts.

A Bit of History

Prior to the early 1960's, canister vacuum cleaners were primarily constructed of stamped steel cases with cast aluminum attachments and trim pieces. Uprights had cast aluminum bases with steel, aluminum or bakelite motor hoods. This made for very durable but heavy vacuum cleaners. Gradually, we saw many trim pieces and motor hoods start to be molded from various plastics. The rubber used earlier to make furniture guards, handle grips and cords was replaced with a soft, flexible synthetic plastic called vinyl (polyvinyl chloride).

I can well remember the very first upright base which was not cast aluminum. It was a pure white lightweight base on a General Electric upright introduced in the early 1960's. We obtained one of these bases to show customers just how tough this new Lexan base developed General Electric really was. We jumped on it, hammered on it, put it through all kinds of abuse, and it still didn't break. This new Lexan polycarbonate resin discovered by Dan Fox at General Electric in 1953 and later used to make this new base started a new trend in the vacuum cleaner industry. Eureka vacuums started using Lexan for their upright bases around 1975 and continues to do so even today for those with the Sanitaire brand name. Hoover and most other companies switched to using a similar high impact plastic base shortly after that.

Around 1966 Eureka developed a new canister series with a case made of high impact plastics instead of steel. It was quite revolutionary in design and construction with a shape like a flying saucer, having a hose that wrapped around the middle. A number of these were sold but the idea just didn't seem to fly. After that series they went back to exclusively using steel for canister cases for many years. Then around 1985 Eureka came out with their award winning plastic Mighty Mite compact canister series and their full sized Express series, both of which had all plastic cases. After overcoming a few glitches, like wheels breaking and falling off while still on the assembly line, these new series did well and lead to their current designs and construction. Hoover and most other companies switched to plastics for their case construction around the same time.

Today's Uses of Structural Materials

Most upright and canister cases are now constructed primarily of ABS plastics (acrylonitrile-butadiene-styrene) with steel, polycarbonates and other high impact plastics used where additional strength is needed. ABS plastic works well for the large case designs where an economical, lightweight and tough material is needed. It is basically polystyrene except that a small amount of styrene-butadiene rubber for better high impact resistance and acrylonitrile for hardening are added to the styrene before it is polymerized. This allows it to flex under impact while still being rigid enough to keep the required shape.

Parts made with Lexan and other polycarbonates are extremely tough with the ability to maintain their physical shapes even under great stresses over a wide range of temperatures. This along with their ability to flex slightly with impact makes them ideal for the main base on uprights as well as the suction fan in dirty-air upright designs. Eureka uses Lexan in the bases and fans of their Professional and Commercial Sanitaire uprights. By using Lexan and Steel extensively in their construction, Sanitaire uprights are very durable even with hard commercial use.

A few vacuum cleaners, like the Kirby and TriStar still have metal main cases. Kirby uses cast aluminum for the housings on their metal uprights. The Tristar has a cast manganese-aluminum alloy case which is extremely tough. Kirby and TriStar are sold exclusively by in-home demonstrations. Some central vacuum systems use a combination of steel and ABS plastics while others are all steel or aluminum.

Various Plastics used in External Structures

There are a number of synthetic resins used in constructing vacuum cleaners. They are created primarily from petroleum derivatives through a process called polymerization. It is a process in which small molecules called monomers are linked to form giant long-chain molecules called polymers. This is done by combining chemical compounds, often with the application of pressure and heat, to cause a chemical reaction which links the individual monomers together to form long-chain molecules. These are entangled with each other and considerable force is needed to disentangle them. These polymer resins are commonly called plastics since they can be molded and shaped. In thermoplastic resins, when heated, the chains move apart enough to permit them to slide over one another. This allows thermoplastics to be melted, then molded or otherwise shaped into usable items. Thermosetting resins, like epoxy and bakelite, can not be melted over and over again for recycling like the thermoplastic resins are. The following is a list of the more common plastics used for vacuum cleaner external structures:

Concluding Remarks

There was a time when we, being very quality oriented, had very little confidence in the plastic cases and trim used on some vacuum cleaners. As time passed and better plastics were developed and used, we found that metal construction wasn't always necessary for long, low maintenance vacuum cleaner life spans. Part designs and types of plastics used for them are still critical for good durability. Generally the more expensive a vacuum cleaner is, the better the design, plastics and other materials which go into making it are. Discerning whether plastic parts are made of a very tough polycarbonate, a more economical ABS plastic or a different plastic is usually a difficult task. A knowledgeable salesperson or technician, like those at Ristenbatt Vacuum Cleaner Service, is probably your best source for learning which materials are used in the construction of various vacuum cleaners.

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