How custom products are made

Tooling in Manufacturing

1) Definition: Specific equipment or machinery created solely for the manufacturing of a specific part or assembly. The common categories of tooling includes fixtures, jigs, gauges, molds, dies, cutting equipment and patterns.

2) Tooling may be classified by the maturity of parts or assemblies that are being manufactured: prototype tooling, short run tooling, and production tooling.

3)Tooling can be broken down into two broad categories — soft and hard. Soft tools are intended for prototypes or short run production. Hard tools are intended for higher volume production applications. One example is where urethane molds are used to produce parts from silicone (soft tooling), whereas injection molding produces parts from steel or aluminum (hard tooling). In some cases, soft tools can be 3D printed rather than a more time consuming and expensive investment in aluminum or steel tools.

4) Tool Design Objectives:
-Reduce manufacturing cost
-Increase production capacity
-Deliver quality parts repeatedly to specification
-Tooling must be safe and ergonomic
-Tooling should be easily cleaned and maintained

5) Economical Manufacturing Lot Sizes and Order Quantities: Economical manufacturing lot sizes and order quantities are calculated to obtain the minimum total unit cost of a given part or assembly. The minimum manufacturing cost is reached when the costs of planning, ordering, setting up, handling, and tooling equal the costs of inventorying finished parts. The manufacturing cost scenarios may be equated and the lot size determined by mathematical calculation.

Economic Order Quantity, EOQ = the square root of ([2*D*O] / [C*UMC])

where:
D = Annual unit demand
O = Setup and Order costs per purchase
C = Carrying costs per unit
UMC = Landed unit manufacturing cost

Example:
O, Setup and order cost = $500
D, Annual demand = 1,000 pieces
C, Annual carrying cost = 14%
UMC, Landed cost per unit = $100

EOQ = sqrt [(2*$500*1,000)/(.14*$100)]= sqrt [$1,000,000/$14] = 267 units

6) Tooling Materials:

PHYSICAL PROPERTIES: The physical properties of a material control how it will react under certain conditions. Physical properties are natural in the material and cannot be permanently altered without changing the material itself. These properties include: density, color, thermal and electrical conductivity, coefficient of thermal expansion, and melting point.

Density: The density of a material is a measure of its mass per unit volume, typically measured in units of lb/in.3 (g/mm3 ). Density is important to consider when the weight of a tool needs to be minimized.
Color: Color is the natural tint contained throughout the material. For example, steels are normally a silver-gray color and copper is usually a reddish brown.
Thermal and Electrical Conductivity: Thermal conductivity and electrical conductivity measure how quickly or slowly a specific material conducts heat or electricity. Aluminum and copper, for example, have a high rate of thermal and electrical conductivity, while nickel and chromium have a comparatively low rate.
Coefficient of Thermal Expansion: The coefficient of thermal expansion is a measure of how a material expands when exposed to heat. Materials such as aluminum, zinc, and lead have a high rate of expansion, while carbon and silicon expand very little when heated. Using materials with low coefficients of thermal expansion is important when dimensional accuracy is critical. Specifying materials with differing rates of thermal expansion can cause problems in constructing and using tools.
Melting Point: The melting point is the temperature at which a material changes from a solid to a liquid state.

MECHANICAL PROPERTIES: The mechanical properties of a material can be permanently altered by thermal or mechanical treatment. These properties include strength, hardness, toughness, plasticity, ductility, malleability, and modulus of elasticity.
Strength: Strength is the ability of a material to resist deformation. The most common units used to designate strength are pounds per square inch (psi) and kiloPascals (kPa). When designing tools, the principal categories to be most concerned with are a material’s ultimate tensile strength, compressive strength, shear strength, and yield strength.
Ultimate Tensile Strength: Ultimate tensile strength is the value obtained by dividing the maximum load observed during tensile testing by the specimen’s cross-sectional area before testing. A material’s ultimate tensile strength is an important property to consider when designing large fixtures or other tooling. It is of lesser importance in tools and dies except where soft- or medium hard ferrous or nonferrous materials are used. The tensile tests successfully made on tool steel involve the use of tempering temperatures much higher than those typically used on tools. Tool steels for hot work, fatigue, or impact applications are usually specified at lower hardness levels. The tensile properties of tool steels can be obtained from data books or vendor literature.
Compressive Strength: Compressive strength plays an important role in tool design. It is the maximum stress that a metal, subjected to compression, can withstand without fracture bending or bulging. The compressive strength test is used on hardened tool steels, especially at high hardness levels. For all ductile materials, the specimens flatten out under load, and there is no well-marked fracture. For these materials, compressive strength is usually equal to tensile strength.
Shear Strength: The shear strength of a material is important to consider when designing tools that will be subjected to shear loads or torsion loads. Shear strength is defined as the stress necessary to cause failure in shear loading (or torsion loading). For most steels, :the shear strength is approximately 50–60% of the alloy’s tensile yield strength. Shear strengths are measured in units of lb/in.2 (psi) or kN/m2 (kPa).
Yield Strength The yield strength of a material is often the most important property to consider.  Measured in units of lb/in.2 (psi) or kN/m2 (kPa), yield strength is the stress level at which an alloy will show permanent elongation after the stress has been removed. A typical yield strength reported is 0.2%, which indicates that the stress produced 0.2% elongation in a 2-in. (50.8-mm) test specimen. Therefore, if permanent deformation is not acceptable for a given application, the stresses that a component is subjected to must be below the yield strength of the alloy. Heat treatments can be used to increase or decrease the yield strengths of alloys.
Hardness: Hardness is the ability of the material to resist penetration or withstand abrasion. It is an important property in selecting tool materials. However, hardness alone does not determine the wear or abrasion resistance of a material. In alloy steels, especially tool steels, the resistance to wear or abrasion varies with alloy content. Hardness scales have been developed, each covering a separate range of hardness for different materials. Rockwell Hardness Rockwell hardness is the most widely used method for measuring the hardness of steel. The Rockwell hardness test is conducted by using a dead weight that acts through a series of levers to force a penetrator into the surface of the metal being tested. The softer the metal being tested, the deeper it will be penetrated with a given load. The dial gage does not directly read the depth of penetration, but shows scales of Rockwell numbers instead. A variety of loads and penetrators can be used, each designated by a different letter and the relative hardness or softness measured. Two types of penetrators are used in Rockwell hardness testing: a diamond cone, known as a brale, for hard materials such as tool steel, and a hardened steel ball for soft materials. Brinell Hardness The Brinell hardness method of measurement is much older than the Rockwell method. It operates similarly to the Rockwell ball-test principle. In the Brinell machine, a 10 mm (.39 in.) steel ball is forced into the material being tested under a load of up to 3,000 kg (6,600 lb). Instead of measuring the penetration, the diameter of the impression in the test piece is measured using a small hand microscope with a lens calibrated in millimeters. The measured diameter is converted into a Brinell hardness number by using a table. The Brinell hardness measurement is most useful on soft and medium-hard materials. On steels of high hardness, the impression is so small that it is difficult to read; therefore, the Rockwell test is used more commonly for such materials. A comparison of the designations for each system, as well as other hardness tests, is shown in Table 2-1. Toughness: Toughness is the ability of a material to resist fracture when subjected to impact loads (sudden rapid loads). Materials that have high toughness must have a combination of high strength and high ductility. Those with high strength but little ductility have low toughness.
Plasticity: Plasticity is the property of a material that allows it to be extensively deformed without fracture. Two general categories of plasticity are ductility and malleability.  Ductility is the property of a material that allows it to be stretched or drawn with a tensional force without fracture or rupture.
Malleability is the property of a material that permits it to be hammered or rolled without fracture or rupture
Modulus of Elasticity: The modulus of elasticity is a measure of the elastic stiffness of a material. It is a ratio of the stress to the strain in the elastic region of a tensile test. The modulus of elasticity determines how much a material will elastically deflect under an applied load. For alloys within the same family, the modulus of elasticity does not vary (for example, the modulus of all steels is 30 × 106 psi; the modulus of all aluminum alloys is 10.5 × 106 psi). The modulus of elasticity is not affected by heat treatment.

General Categories of Tooling Materials: Ferrous: Carbon steels, alloy steels, and cast irons are commonly used for jigs, fixtures, and other tools Non-Ferrous: Non-Ferrous materials, such as aluminum, are used where weight reduction or non-magnetic properties are requirements. Non-Ferrous materials, such as aluminum, may also be used to reduce tooling cost in a low volume production situation. Non-Metallic: Nonmetallic tool materials are commonly used where the cost of using tool steels or similar materials would not be economically practical. Non-metallic 3D printed tools are gaining in popularity due to the low cost of these tools and the ability to deliver tools and make changes quickly. Tool management is needed in manufacturing such that the information regarding the tools on hand can be uniformly organized and integrated. The information is stored in a database and is registered and applied using tool management. Tool data management consists of specific data fields, graphics and parameters that are essential in production, as opposed to managing general production equipment.