Step 49: Phillips® Recess
br]]This cross drive screw story starts when Henry Phillips purchased a crude form of a cruciform-recessed screw head concept from an Oregon inventor named J.P. Thompson.
Henry F. Phillips (1890 to 1958), a U.S. businessman from Portland, Oregon, has the honor of having the Phillips head screw and screwdriver named after him.
Phillips developed Thompsons" invention screw into a workable form. Phillips had come up with a recessed cross screw designed for efficiency on an auto assembly line. The idea was that the screwdriver would turn the screw with increasing force until the tip of the driver popped out, called camout. When tightening a Phillips screw with a Phillips screwdriver you will notice that when the torque gets to be too strong, the screwdriver winds itself out of the screw so the screw head would not be ruined or brake off.
Phillips also founded the Phillips Screw Company in Oregon in 1933, but never actually made screws. He had called on every established screw manufacturer in the US and was told simply that the screw could not be made. Screw makers of the 1930s dismissed the Phillips concept since it calls for a relatively complex recessed socket shape in the head of the screw; as distinct from the simple milled slot of a slotted type screw.
Phillips then called on the American Screw Company, a newcomer to the industry whose new president, Eugene Clark, personally became interested in the new product, despite the opposition of his engineers, who like others in the industry had insisted it could not be made. According to one printed report, the president of American Screw Company said: "I finally told my head men that I would put on pension all who insisted it could not be done. After that an efficient method was evolved to manufacture the fasteners and now we have licensed all other major companies to use it."
Use of the Phillips screws spread through the automobile industry at a rapid rate. By 1939 it was used by all but two automobile manufacturers. By 1940, Phillips" screws were used by the entire automotive industry, although one major manufacturer still would not use them on its passenger cars. Gradually the Phillips screw and screwdriver worked their way into other industrial applications; then consumer products, and eventually showed up in hardware stores.
The American Screw Company spent approximately $500,000 in the 1930s to produce the Phillips screw and obtained patents on the manufacturing methods. It was the sole licenser of the process. By 1940 10 American and 10 foreign companies were licensed to manufacture the screw. Although Henry Phillips received patents for the drive design in 1936 (US Patent #2,046,343, US Patents #2,046,837 to 2,046,840), it was so widely copied that by 1949 Phillips lost his patent ("exclusive" protection would only have lasted until 1956 anyway.)
Phillips' major contribution was in driving the crosshead concept forward to the point where it was adopted by screwmakers and many automobile companies. Henry Phillips died in 1958 at the age of sixty-eight.
The Phillips system was invented for use in assembling aluminum aircraft, with the object of preventing assemblers from tightening screws so tightly that the aluminum threads strip. The driver will cam out before that happens. The Phillips screwdriver has four simple slots cut out of it, each slot is the result of two machining processes at right angles. The result of this process is that the arms of the cross are tapered and has slightly rounded corners in the tool recess. Phillips is designed so that when excess torque is applied it will cam-out rather than ream the recess or destroy the bit. The driver has a 57° point with a blunt tip, tapered wings. Identified in ANSI standards as type I.
In all cross drive systems the driver will self-align with the fastener. The tapered design that allows camout can become a problem as the tooling that forges the recess in the head of the screws begins to show signs of wear. The recess becomes more and more shallow, which means the driver will bottom-out too soon and will cause the driver to cam-out early. Another problem is even though the ease to insert, Phillips screws can be tough to get back out. The main disadvantage is the screwdriver pops out too readily, stripping the screw, gouging the work, and in general transferring all the problems that were formerly with the Slot design. Consumers are likely to think that any screw head with a cross drive recess is a Phillips which can lead to other problems.[[br]]