Delivery Engineered Solutions MES Die Castings Design and Specification Guide Rev 1 – 9-2017 625 Bear Run Ln Lewis Center, OH 43035 Phone: 740-201-8112 www.mesinc.net KEY DESIGN DECISION Matching Material Properties STEPS Pure aluminum is rather weak and malleable on its own. But mixed with other metals such as silicon, iron, copper, magnesium, manganese, or zinc strengthens and brings other benefits to the metal. Adding silicon and magnesium to aluminum, for example, results in an alloy that is extremely resistant to corrosion. There Matching Material Properties are 530 different alloy compositions with more compositions being created and registered every year. The versatility that aluminum alloys offer is undeniable, and the advantages of A380 make it one of the most widely used alloy for manufacturing and die casting. Die & Unit Die Construction Die casting materials are precisely formulated metal alloys which offer the mechanical properties of medium-strength metals. They are generally several times as strong and many times more rigid than plastics, and their mechanical properties compare favorably with powdered iron, brass, and screw- Minimizing Part Porosity machined steel. Designing for proper strength in a product depends on two main factors: strength of the material selected Preplanning Post-Cast Machining and configuration of the part. Die casting alloys offer a wide range of as-cast material strengths, ranging as high as 54 ksi (372 MPa) ultimate tensile. The designer can usually develop sufficient strength in critical features simply by providing Tolerancing Guidelines adequate wall thickness. Where additional strength is required, reinforcing features such as ribs, flanges and locally thickened sections can be accurately computed and precisely cast. Metal Extension (Flash) Guidelines The die casting process allows the product designer freedom to create extremely intricate contours, varying the wall thicknesses over various sectors of the product. Where strength requirements are not critical, MES high-tech die casting can produce rigid components with ultrathin walls. As a result, the As-Cast Finish Guidelines designer has much more latitude with die casting than with plastics, powdered metals, or stampings to design relatively thick walls for strength in some areas, and very thin walls for conserving material in others. Further Design Assistance MES offers the designer material choices in all of the major non-ferrous alloy categories: aluminum, magnesium and zinc. Die Flow Simulation Aluminum Alloy (See the layout for this per attached JPEG) Die casting alloy Al 380 is the most widely used of the aluminum die casting alloys, offering the best combination of properties and ease of production. If offers significant benefits including best combination of casting, mechanical and thermal properties, excellent fluidity, pressure tightness and resistance to hot cracking. It is used for a wide variety of products including but not limited to lighting, automotive, housing and agricultural industries Other alloys including but not limited to A360, A383, A384, A390 and A413 are also used frequently based on the applications Zinc (ZAMAK) Alloys “We are Zinc alloys used in die casting development possess properties that make production simple, transforming age while providing an end-product that is durable. Zinc’s strength and hardness administer high impact strength and stability that make assembly uncomplicated. The high ductility of zinc old industrial alloys is ideal for the die casting process with a strong ability to be cast without fracturing under pressure. Zinc offers unmatched electrical and thermal conductivity while maintaining commodity physical strength, strong stability and corrosion resistance. supply chain Most common grades include Zamak 2, Zamak 3, Zamak 5, Zamak 7. using our IT and data analytics Magnesium Alloy systems” Magnesium is the lightest commonly used structural metal. Its use in die cast parts has grown dramatically, often replacing plastic parts with greater strength and rigidity at no -----MES, INC. weight penalty. Mg alloy AZ91D is the most widely-used magnesium die casting alloy, offering high-purity with excellent corrosion resistance, excellent strength and excellent castability. Corrosion resistance in AZ91D is achieved by enforcing strict limits on metallic impurities. Magnesium’s high cost limits it to weight sensitive applications in aerospace and automotive industries. 1 MES Design and Specification Guide KEY DESIGN DECISION MATERIAL PROPERTIES & NOMINAL CHEMISTRY STEPS Table 1 Typical Material Properties: Die Casting Alloys & Selected Plastics Typical alloy values based on “as-cast” characteristics for separately die cast specimens, not specimens cut from production die castings. (2006 NADCA Standards. Sec. 3) Matching Material Properties Die Casting Alloys Thermoplastics Commercial: AI 380 Mg Zn 3 ZA-8 Polycarbon AZ910D ate Die & Unit Die Construction ANSI/AA: 380.0 AG-40A MECHANICAL PROPERTIES Ultimate Tensile Minimizing Part Porosity ksi 46 34 41 54 19 (MPa) (320) (230) (283) (372) (130) Yield Strength○A 23 23 32 41-43 - - Preplanning Post-Cast Machining ksi (MPa) (160) (160) (221) (283-296) Elongation % in 2 in. (51 mm) 3.5 3 10 6-10 3-5○H Tolerancing Guidelines Hardness_ BHN 80 75 82 100-106 - - Shear Strength Metal Extension (Flash) Guidelines ksi 28 20 31 40 10.5 (MPa) (190) (140) (214) (275) (72) Impact Strength 3 1.6 43 F 24-35 E 2 I As-Cast Finish Guidelines ft-lb ○ ○ ○ (J) (4) (2.2) (58) (32-48) (100) Fatigue Strength© ksi 20 10 6.9 15 6○J Further Design Assistance (MPa) (140) (70) (47.6) (103) (40) Young’s Modulus psi x 106 10.3 6.5 ○G 12.4 1.25 Die Flow Simulation (GPa) (71) (45) (85.5) (8.6) PHYSICAL PROPERTIES Density lb/in3 0.099 0.066 0.24 0.227 0.052 (g/cm3) (2.74) (1.81) (6.6) (6.3) (1.43) Melting Range 1000-1100 875-1105 718-728 707-759 - - °F (540-595) (470-595) (381-387) (375-404) (°C) Specific Heat BTU/lb°F 0.230 0.25 0.10 0.104 0.27 (J/kg°C) (963) (1050) (419) (435) Coefficient of Thermal Expansion μ in./in./°F x 10-6 12.2 13.8 15.2 12.9 12.1 (μ m/m°K) (22.0) (25.0) (27.4) 23.2 (22) Thermal Conductivity BTU/ft hr °F 55.6 41.8© 65.3 66.3 150○K (W/m°K) (96.2) (72) (113) (115) (0.21) Electrical Conductivity % IACS 27 n/a 27.0 27.7 23 Electrical Resistivity○E n/a 35.8 n/a n/a - - μ Ω in. (14.1) (μ Ω cm) Table 2 Nominal Chemical Composition: Die Casting Alloys For detailed chemical composition, request appropriate MES Instant Fax Line Document. Nominal Comp: Cu 3.5 Al 9.0 Al 4.0 Al 8.4 Si 8.5 Zn 0.7 Mg 0.035 Mg 0.023 Mn 0.2 Cu 1.0 With mechanical properties, note die casting alloys 380.0, A380.0, 383.0 and 384.0 are substantially interchangeable. ○A 0.2% offset ○B 500 kg load, 10mm ball ○C Rotary Bend 5 x 107/108 cycles ○D Notched Charpy. ○E AT 68°F (20°C)○F ASTM E 23 unnotched 0.25 in. die cast bar ○G Varies with stress level; applicable only for short-duration loads. Use 107 as a first approximation. ○H At rupture ○I Izod notched1/8”(3.2mm) ft.lb. (J/M) ○J ASTM D671, 2.5mm cycles. ○K Btu-in/h-ft2-°F 2 MES Design and Specification Guide KEY DESIGN DECISION Die & Unit Die Construction STEPS Die casting tool has four main components – Unit Holder, Cavity Block, Replaceable Cavity Unit and Cavity Insert. Matching Material Properties Multiple-cavity dies can be used to increase production rates substantially; in some cases, the use of multiple cavities may limit the use of certain moving core slide operations. Die & Unit Die Construction MES unit dies are standardized unit die holders into which replaceable die cavity “units” can be inserted. These replaceable units can be removed from, or placed into, a unit die holder without removing the unit frame from the die casting machine. MES unit dies can significantly reduce die construction costs at smaller volumes. They are available in single and double unit holders. Minimizing Part Porosity The limitations of unit dies are that they generally can only accommodate the production of smaller-sized parts, and they restrict, or may eliminate, the use of moving core slides. The configuration of Preplanning Post-Cast Machining interchangeable unit die inserts, with the resulting limited die area for core slide functions, makes unit dies most appropriate for less complex product designs. While any die casting die is a major investment, the aggregate manufacturing cost of a component, Tolerancing Guidelines through final finishing and assembly, should be one of the key production decision criteria. The elimination of secondary machining, cosmetic finishing and assembly operations can often cost justify more sophisticated die casting die designs. Metal Extension (Flash) Guidelines As-Cast Finish Guidelines Further Design Assistance Die Flow Simulation Replaceable Die Shoe + Cavity Block or + + Cavity Insert Cavity Unit’ Figure. Components of a unit die illustrate each part of the assembly and the die construction option of a cavity block or a holder block with cavity insert. Cast Features & Die Elements The features that are required of a cast part determine the complexity of the die. The simpler the part, the lower the cost of the die casting tool. Most commonly used materials for aluminum tools are H-10, H-11, and H-13 tool steels. For the proper design of production tooling, pressure tightness, secondary machining and surface finishing specifications must be understood in detail. Areas of the casting subject to machining must be fully discussed at the outset, so that the die can be designed to reduce to an absolute minimum the presence of porosity in those areas.