Goldsmiths began to use hydraulic presses in small shops in the 1940s in North America. Factories have used hydraulic presses for making blanking out parts and forming pieces for some time, and presses in the 150 to 200 ton range are not unusual in jewelry factories today. These need good machine guarding, maintenance and training for the operators.
The smaller shop at the end of the 20th century tends to use slowly operated hydraulic presses in the 12 to 25 ton range for forming operations and some minor blanking, this last often carried out using R.T. or pancake cutting dies. It is the smaller presses I will discuss here.
There are physical hazards like accidents, tripping, pinching injuries, dropping heavy things onto your feet and so on. If it is a powered press then electrical hazards exist. Chemical hazards are present in the form of skin contact with lubricants and hydraulic fluid. Making urethane pads is very dangerous-buy them instead. Never use a bandsaw to cut or heat them when working. The materials used for making dies-liquid steel, Plexiglas etc.- can release chemicals when worked. Plexiglas dies can shatter when under pressure in the press, and shrapnel can fly out from them. Cuts from sharp metal are possible. Mechanical failure of a press (very rare) can cause a severe accident. Home-made presses need careful checking to make sure that they are well designed and that parts cannot fly off precipitously and injure you.
Lubricants and hydraulic fluid in contact with skin can cause dermatitis. Mixing and making the urethane dies is definitely not recommended: the toxic fumes that result are very hazardous. Never cut urethane with a bandsaw or do anything that can heat it up-this releases very toxic fumes. It does not appear to be hazardous to use or touch once set up as a solid. Skin contact and fumes from liquid steel, epoxies and other die-making materials can cause problems. Epoxies are strong sensitizers that cause dermatitis. When cutting Plexiglas, use water as a lubricant, as it reduces fumes and prevents the material from fusing together as you cut. Be aware of other chemical dangers from the die materials you are using.
Because presses operate at 12 to 20 (and even more) tons of pressure there is danger from flying parts if something gives way in the press. Metal can pop suddenly and produces razor-sharp, jagged edges which can cut you severely (voice of experience), particularly if stuck in a die and being forced out with the hands. Eye damage is possible from detonating Plexiglas dies. Powered systems have electrocution and electrical fire hazards.
CTDs are possible in production situations. Otherwise, working heights and suitable work breaks are things to consider. Fire: See “Fire Safety Rules” and “Fire Safety.” Oil storage presents some dangers. If the press is powered the usual electrical fire hazards exist. Exposure routes: Skin contact, inhalation (while working die materials), physical damage, eye damage.
Safety Precautions to Use
Mount the equipment properly. Check and maintain your equipment regularly. Don’t make your own urethane pads. Don’t cut with a bandsaw or heat urethane pads. If you are making stacked Plexiglas dies it is important to use a flexible glue like 3M green latex carpenter’s cement. Because the Plexiglas actually deforms in the press, a harder glue might cause the plastic to crack. I always put duct tape around the edges of the die to act as “blast tape” to protect myself from pieces flying out if the die shatters suddenly. Your best bet is to buy a press built for the purpose, such as those from the Bonny Doon Press company. Be careful of exposure to oils and lubricants.
Substitution Options to Reduce Risk
Outsource, cast, stamp parts, hammer and shape by hand. Hammer into wooden or other molds.
Note: Gareth White has raised some concerns about the threaded rod that is used for home-built hydraulic presses. He feels that the thread rod basically functions as a series of incipient cracks (called a “notching” problem by engineers) and could fail suddenly and dangerously given enough pressure (he is worried in the 30 ton range). I have never heard of this accident but it might be an issue. 12-20 tons, the usual range used in such home-built presses, may not be as dangerous.