How to Make Dies for Hydraulic Presses

As children are familiar with manipulating play-doh to form objects, hydraulic presses use similar principles with metal. But unlike play-doh, these machines exert over 10 tons of force!

It consists of two cylinders; the smaller slave cylinder holds a piston while its counterpart provides force delivery.

Metal

Hydraulic die forming replaces hammer forming by forcing metal into negative die shapes with hydraulic pressure. Commercial presses that use hydraulic die forming may have hydraulic rams capable of exerting up to 3,000,000 lbs per square inch. To get started in metal smithing yourself, it's possible to construct your own simple hydraulic press from an old steel frame and hydraulic jack, with minor modifications as necessary for safe use.

To create a non-conforming die for your hydraulic press, begin by creating the pattern or plaster mold. Lubricate all walls of the container as well as the pattern itself with heavy-duty release agent in order to prevent Devcon from adhering. Next, mix some plastic steel material as instructed on your kit and pour it into your mold; if it does not flow easily around your model when pouring, add Anchor Seal epoxy thinner as required for a thinner mixture.

A finished mold, now known as a "matrice", should be dried either in an oven or simply sitting out on the workbench for four hours until completely dry. At this point, if there are no undercuts present on the mold surface it should be ready for use as a die. Otherwise it must be trimmed back to remove excess material before being sanded to smooth surfaces and cleaned to finish off this step in its creation process.

At this step, draw a design on craft paper that will serve as your "negative" die impression. Keep it simple by drawing an outline without complex shapes. Next, clean and flux a blank plate made of 3/8 to 1/2 thick plexiglass or masonite that has been cut to size for part B (the die). Lay down your template on it along with any flexibleane pieces (if available). Stack all these together securely using tape; secure these layers together by pumping arm of hydraulic jack against upper platen until complete impression forms desired impression is formed. Press entire assembly onto hydraulic ram until desired impression is formed.

Plastic Steel

A hydraulic press can crush most anything, although its effectiveness on stacks of paper is limited. But, its capabilities extend to metal-forming projects such as the bending of sheet metal into different forms for projects such as metal stamping to produce parts such as nuts, bolts and screws, brake levers, valves and bearing races; decorative metal panels (wrought iron and steel furniture components) may also benefit from its use.

Hydraulic presses are widely used for metal forming. Replacing traditional hammer forming, they force metal into negative or constraining die shapes through exerting pressure. There are two general categories of dies used with hydraulic presses: non-conforming silhouette dies; and conforming two-part dies which feature both positive and negative shapes that mate with one another to form one continuous shape.

Hydraulic die forming, also known as cookie cuttering, works like the use of a steel rule die. A steel rule die is a long, bendable strip of metal with a sharp cutting edge that is bent into shape using hydraulic pressure and bent to the desired design by laser cut dieboard made of maple, birch or Lexan (aka bulletproof glass). Foam or rubber ejection is then added alongside this rule in order to push pieces clear of the dieboard after they have been formed.

This method may take longer than using a hammer, but its results are superior. It is ideal for duplicating forms from existing sheet metal forms more precisely and more easily allows achieving fine details with little effort required.

To create a long-lasting die, its materials must be tough. Stainless steel, hard tool steel and cast iron are excellent choices; epoxy-steel with an 80 or 85 durometer durometer rating also proves durable - especially the soft urethane type used with Urethane Files that don't curve its edges while still offering adequate resistance against abrasion. You can usually find such items for sale at hardware stores and tooling supply houses.

Epoxy-Steel

Epoxy-steel dies can be the heart of a hydraulic press when creating pieces requiring precise accuracy and repeatability. They're typically male-female conforming, meaning that they match up exactly with whatever material passes through it, creating an identical piece when finished pressing. For this type of forming process, however, bump cycle capability is typically needed - this allows the press to open up an inch during pressing to release gas from its pressure and prevent part defects such as voids from developing during pressing.

Making a conforming die is straightforward: just create a model of the form you wish to press, attach that model to a flat material such as plexiglass or steel pipe and adhere it there with pastecene for protection and sealing purposes. Next use a punch with great care so as to cut exactly to scribed line with perpendicular sides - and when finished file away approximately an ounce's worth of metal from punch.

Release agent included with the Devcon Plastic Steel Die kit can help prevent epoxy from sticking to either your model or its base material, and keep any dust or other contaminants that could hinder metal press. Once coated, pour in plastic steel mixture according to instructions; allow it to set for four hours before moving on with pressing your metal.

Most machine shops and metal fabricating businesses can supply all the parts for a hydraulic press, including steel plates, springs and jack. You may also choose to build your own press frame out of steel tubing and angle iron with an automotive or hardware store jack for powering it. Either way, once completed this should be strong and capable of pushing large amounts of metal into dies.

Cast Male-Female Conforming Die

If your design requires intricate detail and tight curves, creating a male-female conforming die from metal or pourable epoxy-steel may be more appropriate than using standard masonite dies. Commercially available dies of this nature are capable of withstanding up to 3,000,000 pounds per square inch when pressurized by presses generating up to that pressure; however they tend to be relatively expensive compared with cheaper solutions such as using plaster models or patterns and casting them from them using Devcon, an epoxy steel material designed specifically for tool making applications like tool making dies or metal forming dies is also ideal.

To create a female-female conforming die from a plaster model or pattern, begin by outlining it with pencil and drilling a hole at an undisturbed point in its design. Saw out your desired shape being sure not to cut past your scribed line before filing up to it with straight, perpendicular sides while avoiding rounding. Do this process on both sides until the desired cutout appears - which in this diagram would be part A of it all.

Devcon can be purchased as a liquid in cans from large hardware stores and tooling supply houses, with Plastic Steel from Devcon Corporation of Danvers, Mass being my recommended type. Plastic Steel contains 80% steel powder with 20% epoxy resin binder for ease of hammering without melting or warping - an ideal mold material to create metal forming molds!

Allow the Devcon to harden for four hours before taking steps to extract your punch. Assuming there are no undercuts, your die should easily come away from both model and container without difficulty; otherwise lubricate surface of matrix/walls/container with release agent to increase chances of successful separation and attempt again.

The matrix can also serve as a mold for creating female-female conforming shearing dies, which are great for many applications since they eliminate the time- and labor-intensive task of shaping metal into molds. Shearing dies created this way work best with 22- to 26-gauge soft metals such as copper, silver and gold alloys that have been annealed - perfect for applications where shearing precision is important.