Beating a path to their door

How pneumatics technology is playing a vital role in the automated production of the original wood and wire treadle design mousetrap

James Atkinson invented the world’s first truly effective, wood and wire treadle design mousetrap – the Little Nipper – in 1897. In 1913 the rights were sold to the present producer, Procter Bros, for £2000.

The trap consists of a wooden base in which a series of six wire staples are inserted. These encompass five formed staples designed to the trap spring mechanisms and a single peg to hold the bait. At the bait end two lateral cuts are made to form a hinged platform which is held by two of the staples.

Since its beginning, little has evolved in its design or manufacture, with manual processes, using conventional staple guns and sawing techniques, being predominant in the production cycle.

Now all that is to change with the completion of a fully automated mousetrap manufacturing system designed and made by Coldra Engineering. It enables some new design features to be incorporated into the traps to help improve product longevity and performance.

The machine has been developed to produce both the Little Nipper and an economy version, called the Sentry. In initial production runs the system provided an eight times increase in throughput, with a typical cycle time of 2s/trap.

The system features an eighteen station moving platen configuration, which operates above a continuously rotating table on which the trap bases are automatically clamped.

The wooden bases are loaded into a magazine at the first station, which can be continuously replenished. The stapling heads are designed so that a staple is only laid if a base is under the head.

No pre-formed staples are used, instead each staple is formed from reel feed wire, which is carried on ten uncoilers on the machine’s top gantry.

Each staple station has a dedicated roll of wire, which is fed through a serrator to the station head where it is cut and formed. The wire is serrated on the inside to enhance the grip in the wooden base and the ends of the wire are cut at 45 degrees.

The machine uses the latest electro-pneumatic technology from SMC. In the assembly system there are 32 cylinders, 10 rotary actuators, two, 17 and a six station manifold mounted valve banks.

At each staple station SMC Series CRB rotary actuators feed the wire past a knurling wheel, and then on to the staple head.

At each station head, two Series CQ2, 50mm bore pneumatic cylinders are mounted coaxially to provide a double function of cutting/forming and staple insertion. In essence, as the platen latches to the table, a 35mm stroke CQ2 actuates a cutting and forming mechanism, which then confirms a wood base is present. The second CQ2, with a 15mm stroke then inserts a staple, to a precise depth, into the wood.

The two saw cuts are made at stations four and 16, while other stations perform operations such as crimping and bending one of the trap set staples; and holding the separating treadle using vacuum during sawing.

SMC Pneumatics Tel: 01908 563888