Mold Making  Mold making for metal and plastic injection or casting molding is an craft and sometimes a black art.  As in patents and proprietary trade secrets that are only purchased at a cost.  Low pressure casting or high pressure injection molding molds are built using three main methods: standard - manual machining, EDM machining and CAM - CNC machining.   Standard Machining, in its conventional form, has traditionally has been the only method of building injection molds.  CAM-CNC machining is now the accepted process of making molds be they simple or complex.  CAM-CNC has allowed for more accurate mold tolerance and improved quality in less time.

Mold Materials  
Molding materials are typically constructed from aluminum, hardened steel, pre-hardened steel, and/or beryllium-copper alloy.  The choice of material to build a mold is primarily one of economics.  Steel molds generally cost more to construct, but their longer lifespan will offset the higher initial cost over a higher number of parts made before wearing out. Pre-hardened steel molds are less wear resistant and are used for lower volume requirements or larger components. The steel hardness is typically 38-45 on the Rockwell-C scale. Hardened steel molds are heat treated after machining. These are by far the superior in terms of wear resistance and lifespan. Typical hardness ranges between 50 and 60 Rockwell-C (HRC).
 

Die casting  is a very common metal casting or injection mold process of forcing molten metal usually under high pressure into mold tool cavities (which are desired part shapes machined into dies).   Die castings are typically made from nonferrous metals, specifically zinc, copper, and aluminum alloys although molding of ferrous metal is possible.  Cast parts are often subject to secondary machine and finishing operation prior to final part assembly. Best suited for applications where a large quantity of small to medium sized parts are needed with good detail, surface quality and dimensional consistency including used throughout the power, machine and automotive and motor craft industries. Due to increased raw metal material costs, injection molded plastic has recently been called upon to replaced some die castings applications such as manifolds and gear housing, because of the resulting lower cost and weight issues Plastic parts are a practical alternative if hardness is not required and little strength is needed.

EDM  Electrical discharge machining (EDM) or spark erosion process is also widely used in mold making. EDM is a simple process in which a shaped designed electrode, usually made of copper or graphite, is very slowly lowered with pressure to burn or erode onto the mold surface (many hours), while immersed in paraffin oil.   A voltage applied between the shaped electrode tool and metallic mold causes erosion of the mold surface in the inverse shape of the burning tool.  This process allows for pre-hardened molds to be shaped or tooled so that no post heat treatment is required.  Changes to a hardened mold by conventional drilling and milling normally require annealing to soften the steel, followed by heat treatment to harden it again.   

Annealing, is a metal, heat treating process where the metallic and sometimes chemical crystalline structure is modified, resulting in changes in its properties such as strength and hardness.   The process by heating and maintaining a suitable temperature and then cooling, produces altered materials properties.  Annealing is used to induce ductility, relieve internal stresses, refine the structure and improve cold working properties typically applied to market applications where extreme hardness and toughness are required such as hand tools or a crowbar and large manufacturing metal die stamping tools.

Case Hardening or surface hardening is the process of cold work hardening the surface of a metal, often a low carbon steel, by infusing elements into the material's surface, forming a thin layer of a harder alloy.  Case hardening is usually done after the part has its final shape  

Ductility is a mechanical property which describes how much plastic deformation a material can sustain before a stress fracture occurs. Examples of highly ductile metals are silver, gold, copper, and aluminum. The ductility qualities of steel varies depending on the alloying constituents with increasing levels of carbon, decreases ductility, i.e. the steel becomes more brittle.

Hardening and tempering (quenching and tempering)   Hardening by quenching, a metal, usually a steel or cast iron alloy, the material will be heated into the austenitic crystal phase and then quickly cooled.  Depending on the alloy the desired hardness and ductility, the process must be controlled to avoid surface cracking and distortion with cooling achieved by blown air or other gas (such as nitrogen), oil, polymer dissolved in water, or saltwater bath.  Upon being rapidly cooled, a portion of austentite (dependant on alloy composition) will transform to martensite, a hard brittle crystalline structure.

Sheet Metal  Formed, punched and drilled sheet metal is use extensively as an electronic packaging material. Mechanically strong, it provides excellent structural properties, electromagnetic shielding when the product requires that feature.  Sheet metal is great for prototypes and small production runs with little custom tooling expense.

Punch press is used for forming holes.  Progressive stamping is a manufacturing method that can encompass punching, coining, bending and several ways of modifying the metal, combined with an automatic feeding system. The feeding system pushes a coil of metal through all of the stations of a progressive stamping die. Each station performs one or more operations until a finished part is made per the requirements on the print. The final operation is a cutoff operation, which separates the finished part from the carrying web. The carrying web, along with metal that is punched away in previous operations, is considered scrap metal. A brake press is a special type of machine press that bends sheet metal into shape.

Die   A die &  progressive die is a cold or hot process in which metal is deformed below or above its recrystallization temperature. Specialized presses or working tool used to cut, shape and form metals and plastics and ceramics and glass .Like molds and templates, dies like stamping dies are generally customized and uniquely matched to the product they are used to create. Die block, Punch plate, Blank punch, Pierce punch, Stripper plate, Pilot, Dowel, Back gage, Finger stops. Progressive dies provide different stations for operations to be performed. A common practice is to move the material through the die so it is progressively modified at each station until the final operation ejects a finished part.

Die operations are often named after the specific type of die that performs the operation. For example a bending operation is performed by a bending die. Operations are not limited to one specific die as some dies may incorporate multiple operation types.

Press with bending die

• Bending: The bending operation is the act of bending blanks at a predetermined angle. An example would be an "L" bracket which is a straight piece of metal bent at a 90° angle. The main difference between a forming operation and a bending operation is the bending operation creates a straight line bend (such as a corner in a box) as where a form operation may create a curved bend (such as the bottom of a soda can).
• Blanking: A blanking die produces a flat piece of material by cutting the desired shape in one operation. The finish part is referred to as a blank. Generally a blanking die may only cut the outside contour of a part, often used for parts with no internal features.
  Three benefits to die blanking are:

1. Accuracy. A properly sharpened die, with the correct amount of clearance between the punch and die, will produce a part that holds close dimensional tolerances in relationship to the parts edges.
2. Appearance. Since the part is blanked in one operation, the finish edges of the part produces a uniform appearance as opposed to varying degrees of burnishing from multiple die cutting operations.
3. Flatness. Due to the even compression of the blanking process, the end result is a flat part that may retain a specific level of flatness for additional manufacturing operations.

• Broaching: the process of removing material through the use of multiple cutting teeth, with each tooth cutting behind the other. A broaching die is often used to remove material from parts that are too thick for shaving.
• Bulging: A bulging die expands the closed end of tube through the use of two types of bulging dies. Similar to the way a chefs hat bulges out at the top from the cylindrical band around the chefs head.

1. Bulging fluid dies: Uses water or oil as a vehicle to expand the part.
2. Bulging rubber dies: Uses a rubber pad or block under pressure to move the wall of a work piece.

• Coining: is similar to forming with the main difference being that a coining die may form completely different features on either face of the blank, these features being transferred from the face of the punch or die respectively. The coining die and punch flow the metal by squeezing the blank within a confined area, instead of bending the blank. For example: an Olympic medal that was formed from a coining die may have a flat surface on the back and a raised feature on the front. If the medal was formed (or embossed), the surface on the back would be the reverse image of the front.
• Compound operations: Compound dies perform multiple operations on the part. The compound operation is the act of implementing more than one operation during the press cycle.
• Compound Die: A type of die that has the die block (matrix) mounted on a punch plate with perforators in the upper die with the inner punch mounted in the lower die set. An inverted type of blanking die that punches upwards, leaving the part sitting on the lower punch (after being shed from the upper matrix on the press return stroke) instead of blanking the part through. A compound die allows the cutting of internal and external part features on a single press stroke.
• Curling: The curling operation is used to roll the material into a curved shape. A door hinge is an example of a part created by a curling die.
• Cut off: Cut off dies are used to cut off excess material from a finished end of a part or to cut off a predetermined length of material strip for additional operations.
• Drawing: The drawing operation is very similar to the forming operation except that the drawing operation undergoes severe plastic deformation and the material of the part extends around the sides. A metal cup with a detailed feature at the bottom is an example of the difference between formed and drawn. The bottom of the cup was formed while the sides were drawn.
• Extruding: Extruding is the act of severely deforming blanks of metal called slugs into finished parts such as an aluminum I-beam. Extrusion dies use extremely high pressure from the punch to squeeze the metal out into the desired form. The difference between cold forming and extrusion is extruded parts do not take shape of the punch.
• Forming: Forming dies bend the blank along a curved surface. An example of a part that has been formed would be the positive end(+) of a AA battery.
• Cold forming (cold heading): process in which metal is deformed by passing it through rollers at a temperature below its recrystallization temperature. Cold rolling increases the yield strength and hardness of a metal by introducing defects into the metal's crystal structure. These defects prevent further slip and can reduce the grain size of the metal,  Cold forming is similar to extruding in that it squeezes the blank material but cold forming uses the punch and the die to create the desired form, extruding does not.
• Roll forming: is a continuous bending operation in which sheet or strip metal is gradually formed in tandem sets of rollers until the desired cross-sectional configuration is obtained. Roll forming is ideal for producing parts with long lengths or in large quantities. (Roof gutters)
• Horning: A horning die provides an arbor or horn which the parts are place for secondary operations.
• Pancake die: A Pancake die is a simple type of manufacturing die that performs blanking and/or piercing. While many dies perform complex procedures simultaneously, a pancake die may only perform one simple procedure with the finished product being removed by hand.
• Piercing: The piercing operation is used to pierce holes in stampings.
• Progressive die: Progressive dies provide different stations for operations to be performed. A common practice is to move the material through the die so it is progressively modified at each station until the final operation ejects a finished part.
• Shaving: The shaving operation removes a small amount of material from the edges of the part to improve the edges finish or part accuracy. (Compare to Trimming).
• Side cam die: Side cams transform vertical motion from the press ram into horizontal or angular motion.
• Sub press operation: Sub-press dies blank and/or form small watch, clock, and instrument parts.
• Swaging: Swaging (necking) is the process of "necking down" a feature on a part. Swaging is the opposite of bulging as it reduces the size of the part. The end of a shell casing that captures the bullet is an example of swaging.
• Trimming: Trimming dies cut away excess or unwanted irregular features from a part, they are usually the last operation performed.
• Thread Rolling process is used for making external threads. A die, which is a hardened tool with the thread profile, is pressed on to a rotating workpiece. As the force is gradually increased, the thread profile is transferred to the workpiece. This process produces screws with greater strength than machined threads due to the cold working, as well as better material yield.

Heat treatment is a method used to alter the physical properties of a metallic material. Heat treatment involves the use of heating, slow cooling or rapidly chilling, sometimes to extreme temperatures, hardening or softening the yield strength, plasticity or ductility of the material.  Heat treatment techniques include annealing,  tempering,  case hardening, precipitation strengthening, and quenching.  Heating and cooling in the raw metallurgical manufacturing processes such as hot forming or welding create natural strain or work hardening, giving the material particular strength qualities. Heat treatment is used to alter these properties.

Mill   A milling machine is used for the complex shaping of metals, plastics and other solid materials. Milling machines can perform a vast number of complex material removing operations, such as: slot cutting, surfacing, planing, drilling, rebating, routing, etc. Cutting fluid is often pumped to the cutting site to cool and lubricate the cut, and chip removal.

Lathe  There are many variants of turning lathes or centering lathe where the work remains fixed and the heads move in an XY axis median direction or face towards the workpiece and machine.  Can perform complex contouring material removing operations, such as: barrel and conical surface cutting, slot cutting, surfacing, drilling, core-outs, etc. Cutting fluid is often pumped to the cutting site to cool and lubricate the cut, and chip removal.

Precipitation hardening,  age hardening or dispersion hardening, is a heat treatment technique used to strengthen materials, including most structural alloys of aluminum, magnesium and titanium, and some stainless steels. There are two precipitation heat treatments: solution heat treating and precipitation heat treating. Solution heat treating or quenching involves formation of a single-phase solid solution  leaving a material softer.  Precipitation heat treating involves the addition of impurity particles to increase a material's strength.   The p recipitation process creates changes in solid solubility with temperature to produce altered chemical crystalline lattice structure. plasticity, softening or hardening the material.  Unlike ordinary tempering, alloys must be kept at elevated temperature for hours to allow precipitation to take place. This time delay is called aging.

Peening is a cold working process where the surface of the metal is blasted by shot pellets or hammering.  This impact process induces compressive stress just below the surface to compensate for the stretching of the surface, reducing tensile stress by inducing compressive stress on the part. Plastic deformation induces a residual compressive stress in a peened surface, along with tensile stress in the interior. When a tensile load is applied on this residual compressed load, the net effect is a reduced amount of stress on the part.  This makes the metal weld better suited for fatigue applications which involve cyclic loads-such as gears, crankshafts etc. The peening application can be applied  done by using a manual hammer.

Work hardening  Work hardening or cold work or strain hardening serves to harden the material's surface. This action helps reduce surface cracks forming, at the surface and provides resistance to abrasion.   When a metal undergoes strain hardening its yield strength increases but its ductility decreases.  On a micro scale, strain hardening increases the number of dislocations in the crystal lattice of the material.  The greater the number of dislocations, the less plastic deformation supporting the have greater yield strength and elasticity beyond the elastic yield stress of the non-strain, work hardened material.

Casting

• Foundry
• Crucible
• Green sand
• Lost wax
• Lost foam
• Refractory
• Investment Casting

Forge Work

• Forge weld
• Anvil
• Forge
• Anneal(ed)
• Pitchrell
• Hardy
• Hardy Hole
• Chipping block
• Carburizing
• Oxidizing
• Furnace

Cutting Tools - Blade Craft

• Tang
• Band saw
• Jig Saw
• Circular Saw ( 8”)
  Table saw ( 10”- 12”)

Welding (See Secondary Operations)

• Arc welding
• MIG welding
• TIG welding
• Oxyacetylene welding

Shop Work/Tools

• Lathe
• Milling machine
• Drill Press
• Shaper
• Guillotine – Shear
• Bender
• Grinding machine
• Arbor press

Other

• Draw
• Hand scrape (flatness)
• Pitch
• Rivet
• Blue brittle
• Etching
• Peen

Call us to discuss your project specifications.