Designing plastic parts for assembly sciencedirect. Thick section core out thick section not recommended recommended typical metal design. Plastic part design for injection molding hanser elibrary. Plastic resin enters the mold through a sprue in the a plate, branches out between the two sides through channels called runners, and enters each part cavity through one or more specialized gates. For the sake of brevity, this article will focus on one type. When designing plastic parts, your team should consist of diverse players, including conceptual designers, stylists, design engineers. Part design guidelines for injection molded thermoplastics. Whether you are just entering the field, or are a seasoned plastic parts designer, designing plastic parts for assembly is an excellent tool that will facilitate costeffec tive design decisions, and help to ensure that the plastic parts and products you design stand up under use. Designing plastic parts for assembly hanser publications. Tres book isbn 9781569905555 hanser hanser publishers, munich hanser publications, cincinnati. Coring and wall thickness resin material inches abs 0. This will ultimately reduce material and manufacturing costs. The result is a digital prototype of your product, one you can explore in detail.
Concept to finished part design process like a successful play in football, successful plastic product design and production requires team effort and a welldeveloped strategy. Typical property table provides data on typical physical properties for each plastic. The detailed yet simplified discussion of material selection, manufacturing techniques, and assembly procedures enables the. The designers and engineers at api have over 250 combined years of experience in designing parts for plastic injection molding, selecting materials, and. Trantina, design with plastics, materials selection and design, volume 20, asm handbook, asm international, 1997, pages 639 to 647 the key to any successful part development is the proper choice of material, process, and design matched to the part performance requirements. Tres designing plastic parts for assembly book isbn.
Api is experienced in molding all thermoplastics, specializing in engineering, high performance, and glass reinforced resins. Jul 20, 2016 rex plastics product development plastic part design fundamentals gates and parting lines. Since plastics shrink when cooled, it is common for parts to shrink or grip tightly to cores. Once the use of plastic is assumed, the chapter provides support for the determination of which of the four major plastics manufacturing processes should be used. Read this article to know the advantages of injection molding. Draft angle design is an important factor when designing plastic parts. Aug 18, 2014 the essentials of better plastic part design cadimensions, inc. If youve ever built a plastic model kit, youve seen and know at least something about injection molding. Injection molding is one of the most widely used processes for fabrication of plastic parts.
Request pdf design of plastic parts practical considerations for plastic part design are presented beginning with an overview of advantages of polymeric. Threads plastic threads used for joining parts can be machined or moldedin. The ability to design plastic parts requires knowledge of material propertiesper formance indicators that are not design or geom etry dependentrather than. Processing conditions for plastic injection molding. Variations and evolutions of these appear in nearly every plastic part design book, guide or reference. Injection molded plastic parts offer an important combination of flexibility, toughness, and chemical resistance for cost effective, longterm performance in a range of applications. The strength of the snapfit joint depends on the material used, its geometry and the forces acting on the joint. This creates higher contact pressure on the core surface and increases friction between the core and the part, thus making ejection of the part from the mold difficult. We recommendedusing the guidelines in the table to the right as thicknesses vary by material.
Almost every plastic part around you was manufactured using injection molding. Designing plastic parts is a little different from designing metal parts. Designing plastic parts and components involve implementing wide knowledge from different engineering areas. The essentials of better plastic part design youtube. Injection molded parts can be molded to a high quality standard by focusing on these areas of plastic. Because of shrinkage of plastic material, injection molded parts have a tendency to shrink onto a core. The raw plastic is melted in the injection molding machine and then poured into the mold where it is allowed to cool and solidify. Design consideration for plastic part design and its. Design considerations draft plastic parts are always designed with a taper or draft in the direction of mold movement to allow part ejection or removal from the mold. When designing moldedin threads, avoid feathered edges and include radiused roots in order to minimize stress concentrations p and to keep the walls uniform. However, not every plastic part design can be efficiently injection molded.
Whenever you begin a design project involving plastic parts, where your end goal is to have the component injection molded, youll want to consider some things on the front end of your design process that will allow for time and money to be saved during the production phase of your project. Plastic component design considerations to insure a quality final product, it is necessary to start out with quality components. Design and engineering our engineering department begins with your design or concepts to develop a 3d part design. The intersection of the base of the boss with the nominal wall is typically stressed and stress concentration increases if no radii are provided. Some general guidance is then provided about the design of plastic parts for stiffness and strength. Injection molding offers high repeatability and good design flexibility. A snapfit joint can be designed so it is easily separated or so that it is inseparable, without breaking one of its components.
May 06, 2016 plastic is cheaper and easier to work with. The injection molding process requires the injection molding machine, raw plastic, and the mold. Injection molding has various advantages compared to other plastic manufacturing process. An economical and quick method of joining plastic parts is by a snapfit joint. Goel, shihho chao encyclopedia of life support systems eolss central to the idea of all plastic analysis methods is an implicit assumption that the structure being analyzed is made from ductile materials. Detailed plastic product design will always require detailed knowledge of the application, the processing method and the selected plastic. Injection molding is so popular, because of the dramatically low cost per unit when manufacturing high volumes. Plastic part design guidelines for injection molding. So working with us early in the design process is important. For the engineering and design team at urbe, it was a no brainier to utilize plastic components for the fenders and battery hub in order to ramp up its. Further, thin parts weigh less, using less plastic per part. Design and manufacturing of plastic injection mould. There are several styles of gates that are commonly used in molding. Designing plastic parts for assembly hanser elibrary.
Each plastic part design must have a gate, or an opening that allows the molten plastic to be injected into the cavity of the mold. Design tips get quick advice on creating plastic, metal, and elastomeric parts for 3d printing, cnc machining, sheet metal fabrication, and injection molding. Thick section thick section not recommended recommended prefered plastic design. The designers and engineers at api have over 250 combined years of experience in designing parts for plastic injection molding, selecting materials, and processing resins specializing in engineering and high performance resins. Injection molding process is the best way to manufacture plastic parts for high volumes and low cost.
General input on the best molding method for the design concept should be sought early in the design process so the part shape can be optimized accordingly. Highly durable, endless color options and of course, an inexpensive option when manufactured in high volumes. May 23, 2015 these benefits in terms of cost reduction, ease of manufacturing through injection mold for the higher quantity and superior quality and the appearance of the parts contribute to extensive adoption of plastic in the product development by the industry. Several decades ago, plastic part design guidelines began to emerge that tried to address some of the more obvious problems in producing injection molded plastic parts. The design of a plastic part and the selection of the plastics manufacturing process are extremely interdependent. Loctite design guide for bonding plastic ellsworth. Metal parts are often designed with thick walls, while plastic parts should ideally maintain uniform wall thickness for uniform flow and less shrinkage. Structral engineering and geomechanics plastic versus elastic design of steel structures sutat leelataviwat, subhash c. Without digital prototyping, youd need to use more budgetvaporizing physical prototypes, watch time slip away, and get to. When designing parts for injection molding, the manufacturing process is an important consideration. It is intended to give the product designer the basic guideline to design a product that is of high quality and easy to manufacture plastic parts. Design parts with a minimum of per side draft in order to accommodate easier ejection from the mold. On average, the wall thickness of an injection molded part ranges from 2mm to 4mm. Jul 02, 2018 plastic parts are now commonplace in consumer product design, and for good reason.
Plastic design issues injection molded plastic parts offer an important combination of flexibility, toughness, and chemical resistance for cost effective, longterm performance in a wide range of applications. Blow molding design guideline blow molding design guideline 3 radii corners material will freeze when it comes into contact with the mold, causing it to stretch into corners if parison is trapped pinched off at parting line, it must stretch into the cavity preblowing the parison prior to mold closure helps minimize stretch. There are many things that must be carefully considered and planned for. This information can only be provided by raw materials suppliers, specialist plastics product designers and plastics processors but there is a need to get the basics of the product design right in the first. It is particularly important to bear the following factors in mind when designing snap joints. The loctite design guide for bonding plastics, volume 6 3 recycling symbol illustrates the appropriate recycling symbol for the indicated plastic type, when appropriate. For over 22 years, designing plastic parts for assembly has been the definitive guide for both seasoned part designers and novices to the field, facilitating costeffective design decisions and ensuring that the plastic parts and products will stand up under use. Plastic part design for injection molding hanser publications. Plastic part design guidelines for injection molding ensures good quality products. Designing with manufacturability in mind can accelerate production time and reduce production costs. May 30, 2012 new high performance plastics and innovative molding processes make this possible. Parts are specifically designed to meet thermoforming design specifications as well as yours. Minimum radius at base of boss a fillet of a certain minimum radius should be provided at the base of a boss to reduce stress.
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