In developing our Masterkey, we experimented with many different materials to find the best metal to craft our multi-tool. We wanted a high strength and tough metal that would hold up heavy everyday use, but also lightweight and cost-effective. In addition, we wanted to make sure that the black coloring/laser etching would not rub off over time.
(TL;DR? - We use high strength 7075-T6 aluminum for our Masterkey multi-tool, which is stronger than many other alloys. This aluminum is actually used in many modern aircraft parts, unlike some other variants that are marketed as "aircraft grade" today. We also tested our materials through opening a lot - and we mean a lot - of beers.)
Finding the Right Metal
In our search, we came across a number of metal types. Lots of different options were available:
Titanium - ultra-lightweight, high strength, but extremely expensive (many times more than the cost of stainless steel/aluminum), very difficult to machine.
Stainless steel - Heavy, easier to machine than titanium, color powder-coating would rub off over time.
Aluminum - between titanium and steel on weight and cost, easy to machine and anodizing colors don't rub off like powder coating. Can be stronger or softer than steel depending on alloy.
We decided to go with aluminum for our application for its high strength-to-weight ratio, machinability, cost effectiveness, and color anodizing ability (where color is chemically bonded rather than physically sprayed on like in powder coating for steel). However, we knew that we needed to find the right alloy. There are many types of aluminum, and we wanted to make sure we found the right one.
During our search of aluminum alloys, we found many were marketed as "aircraft grade aluminum". What exactly is "aircraft-grade?" It's a term now used loosely to refer to many alloys of aluminum. It's been used so much that it's become in many cases a marketing buzzword. The term originally referred to the aluminum-copper alloys developed around WWI. However, over time, advancement in aluminum has changed the application in which aluminum is used in airframes. In fact some "aircraft grade" aluminum alloys are not widely used in aircraft for structural purposes today.
Not All Aluminum is Made Equal
One of the most common forms of aluminum alloy is 6061 aluminum. It's lightweight, cheap, and easy to machine. While technically labeled as "aircraft grade" (and marketed in many outlets as so), 6061 is much softer than other grades and doesn't hold up well in applications requiring high strength or hardness. In aircraft, it isn’t used in any mission critical parts.
We use 7075-T6 aluminum in our Masterkeys, which is one of the highest strength alloys available. It is much stronger than 6061 aluminum, and also tougher than many steel alloys (at a fraction of the weight). The T6 designation means that the 7075 aluminum is further heat-treated at 450 °C for several hours, quenched, and then aged at 120 °C for another 24 hours. This treatment yields the peak strength of the alloy. Common applications of 7075 aluminum are in commercial and military aircraft airframes, gears and shafts, missile parts, and other structural uses where parts are under high stress and strength is critical.
Putting Rubber to The Road (or Bottler Opener to Cap)
While background research is important, we wanted to make sure that the aluminum we chose actually help up in our applications, and so we conducted a test.
We made two test bottle openers, one with 6061 Aluminum and the other 7075. With each opener, we opened a total of six beer bottles, and reviewed how well each material stood up.
As bottle caps are all different, depending on the makers (some are made from stainless steel while others aluminum), we used a range of different beer bottles from local, craft, and import brands.
Probably the most fun test we conducted...
(No worries, no beer was wasted in the test - our team had a great time enjoying the residuals)
The results were pretty definitive:
Post-test: 7075 (top) vs. 6061 (bottom)
The 6061 test piece had noticeable wear in the contact points against the bottle cap, with the main lever arm distinctly shorter than the 7075, which had no noticeable wear.
Long Term Test:
Here is our Masterkey after opening about 60 or so bottles (the same one used in our Cinco de Mayo video here). Some of the black anodizing has been removed which is normal under regular use, but the aluminum itself has not chipped or scratched.
Long Term Masterkey Test - Key after 60 opens (top) vs. Control (bottom)
That's all for now. We're working on a number of new releases next month, and am very excited to get them launched soon. Stay tuned!