2.008 Design & Manufacturing II The Discrete Parts Manufacturing Lab IV: Product Design Lab V: Tooling Design Lab VI: Tooling Fabrication Lab VII: Parts Production Lab VIII: Product Inspection: Quality & Variation OBJECTIVE 2 INTRODUCTION 2 ORGANIZATION 2 LAB IV: PRODUCT DESIGN 2 LAB V: TOOLING DESIGN 3 LAB VI: TOOLING FABRICATION 3 LAB VII: PARTS PRODUCTION 3 LAB VIII: PRODUCT INSPECTION: QUALITY & VARIATION 3 DELIVERABLES 3Labs IV-VIII OBJECTIVE This exercise requires student teams to design and manufacture a three-part, or four-part yo-yo. The goal is to follow a typical product design/manufacturing sequence. The steps include: 1) Designing a product to be manufactured, 2) Designing the tooling to be used to form the parts for the product, 3) Machining the tooling with computer numerically controlled (CNC) machine tools, 4) Optimizing (tuning) the manufacturing processes, 5) Manufacturing a batch of product, and 6) Characterizing the manufactured products. These exercises provide an opportunity to apply what you have learned about CAD/CAM, to learn about commonly used manufacturing processes, and to recognize some issues concerning the optimization of a manufacturing process. One of the lessons that can be learned by going through this progression is that the process and the tooling impose limitations on the part design. As an example, whether the part is thermoformed or injection molded, it must be easily removable from the forming tool. Thus, we will see that for best results the product and the process (in this case the tooling) must be considered simultaneously. INTRODUCTION Forming processes are used to produce a tremendous variety and quantity of parts. Examples of forming processes for metal include casting and sheet metal forming. Two forming processes for polymeric materials, injection molding and thermoforming, will be the focus of this laboratory sequence. The lessons learned from examining injection molding and thermoforming will be applicable not only to plastic materials, but to metals and ceramics as well. All forming processes have one essential ingredient in common. They all rely on a tool, die, or mold to create the geometry of the finished part. In general, each new part design demands the creation of a new tool or die. This situation contrasts greatly with machining, where a set of cutting tools can be used to create a wide variety of finished shapes. Thus, we see that forming processes are less flexible to design changes than machining processes. However, forming processes result in net shape or near net shape parts. Thus, the use of forming processes is a balance between the cost and time associated with creating the tool or die and lower cost per part when making a large number of parts. ORGANIZATION Since the project will take several weeks to complete, we have broken the exercise into small segments: Labs IV, V, VI, VII, and VIII. During these labs students are organized into groups. Each group will design its product together and should delegate responsibility to specific individuals/teams for the manufacture of each of the component parts you intend to produce. Lab IV: PRODUCT DESIGN Each yo-yo group will design a yo-yo that has two, or three injection molded parts, and one, or two thermoformed parts. The designs, which you submit, are required to specify the increment of interference that you intend, and the dimensional tolerance that you anticipate will provide adequate service. An example of an exploded assembly drawing of a yo-yo can be found in the ‘Lab Handouts’ folder in the course locker. Mold blank dimensions can be found in the ‘Mill Injection Molding Blanks’, and ‘Lathe Injection Molding Blanks’ folders. Prints of the ‘Punch and Die Set’ blanks, as well as a ‘Thermoform Mold Blank’ are in their respective folders. 2.008 - Design & Manufacturing II -2- The Discrete Parts ManufacturingDesign requirements: • Yo-Yos should be made of 2-3 injection-molded parts that snap fit together, and at least 1 thermoformed part • A set of ejector pins can be used if the injection-molded parts are not easily removable from the two-piece molds • Each injection-molded part cannot exceed 2.7 cubic inches in volume • The maximum outside diameter of the injection-molded parts cannot exceed 2.5” in diameter • High impact polystyrene ‘HIPS’ sheet of .020”, .030”, and .040” thickness is provided for thermoformed parts • Polypropylene is provided for the injection-molded parts, various colors are available • Appropriate spec ranges (tolerances) must be specified for the dimensional features of each part Lab V: TOOLING DESIGN Team members will design the molds needed to produce the required parts and use Mastercam to generate “G” code to direct the motion of the machine tools to produce these molds. Team members must confer with teammates to reach agreement on common dimensions and intended interferences to ensure snap-fits. All molds will be machined from aluminum. Ejector pins can be used if the design warrants the need for them. Team members responsible for the thermoformed part will machine their designed shape into a mold blank measuring 3.0” in diameter X .625” thick. They will also have an option to design, and machine a punch-and-die set for trimming the finished part from the material. The punch-and-die set will be made from low carbon steel. Prints for all the blanks, including the punch-and-die blanks are posted in the course locker, as well as a print showing the location and size of the ejector pin holes for the injection-molding blanks. Be sure, when importing your design to the mold blank templates, that you locate the center of the product in the center of the blanks. Lab VI: TOOLING FABRICATION Students will machine their molds using the CNC machine tools in the laboratory. Lab VII: PARTS PRODUCTION Students will use the injection molding and the thermoforming machine to produce enough parts for fifty assembled products. Students are expected to optimize the process for the desired quality features and to become proficient in the operation of the injection molding and thermoforming machines before beginning the production run. Student teams will divide responsibilities to permit molding, trimming and sequence numbering for the creation of a run chart. During the