OET-010 Manufacturing Processes TAG Rubric COURSE OUTLINE

Transcription

1 OET-010 Manufacturing Processes TAG Rubric COURSE OUTLINE MET Objective SURVEY OF MANUFACTURING PROCESSES INSTRUCTOR: STEVE SYKES Mon/Wed 2:30PM 5:15PM OFFICE: (Room 434) TEXT: MODERN MANUFACTURING PROCESSES SME - DAVID L. GOETSCH ssykes@edisonohio.edu 3. Distinguish between different fabrication processes such as welding, fasteners, and adhesives. WEEKLY SCHEDULE OF TOPICS, ACTIVITIES, AND ASSIGNMENTS WEEK DATE LAB/ACTIVITY LECTURE/DEMONSTRATION ASSIGNMENTS 1 1/12 Lecture Brief overview of course Introduction of Manufacturing Processes Manufacturing Safety Chap. 1,17 HO 2 1/19-21 Lecture Engineering Materials, Metals, Physical Metallurgy Chap /26 Lecture Heat Treatment Chap /02 Exam 1, 5 2/09 Lecture Welding/Related Processes Chap /16 Lecture Welding Related Processes Chap /23 Lab Welding Symbols Hand-out 8 3/02 Exam 2 Welding Lab ---- * 3/09 Spring Break /16 Lecture Pattern Making, Casting Processes Chap /23 Lecture/Lab Sand Castings Handout 11 3/30 Lecture Sand Castings (lab) Handout 12 4/06 Exam 3, Lab Field Trip /13 Lecture Metrology, Metal Cutting Theory Chap /20 Lecture/Lab Turning Processes/ Chap /27 Lecture/Lab Milling Processes Chap /04 Exam 4 Final s Week Manufacturing Research Presentation

2 Fillet Weld Base Metal metal to be welded Bond Line the junction of the weld metal and the base metal Depth of Fusion the distance that fusion extends into the base metal Face of Weld 5 2 the exposed surface of a weld on the side from which the weld was made Leg of Fillet Weld the distance from the root of the joint to the toe of the fillet weld Root of Weld the shortest distance from the root of the fillet weld to its face Throat of Fillet Weld the point or points at which the bottom of the weld intersects the base metal surface or surfaces Toe of a Weld the junction between the face of a weld and the base metal

3 Groove Weld Bevel Angle the angle formed between the prepared edge of a member and a plane perpendicular to the surface of a member Groove Angle the total included angle of the groove between parts to be joined by a groove weld Groove Face the surface of a member included in the groove Root Face that portion of the groove face adjacent to the root of the joint Root Opening the separation between the members to be joined at the root of the joint 3

4 Forces in Welding

5 Shielded Metal Arc Welding (SMAW) an arc welding process which produces coalescence of metals by heating them wit electrode and the work. Shielding is obtained from decomposition of the electrode used and filler metal is obtained from the electrode. (Stick ) 5

6 Standard Location of Element of a Welding Symbol 6

7 Weld Fillet Gage Checking Fillet Throat Size Checking Fillet Leg Size

8 Fasteners in Aviation Fastener Overview: Types of Fastener: Permanent Fastening Welding Adhesive Bonding Riveting Temporary Fastening Threaded Non-Threaded

9 Permanent Fastening Welding Adhesive Bonding Riveting 9

10 Adhesive Bonding 10 Adhesive bonded composite test strips

11 Riveting Rivet joints on a Cessna

12 Adhesives and Glues

13 Definition An adhesive is a compound that adheres or bonds two items together. The use of the terms adhesive and glue is confused. Historically natural compounds used as an adhesive were called glues Historically, glue only referred to protein colloids prepared from animal tissues. Synthetic compounds were called adhesives. Today the meaning of the term adhesive has been extended to any type of glue-like substances that is used to attach one material to another.

14 History of Adhesives The first adhesives were gums and other plant resins. Vegetable gums: Guar gum Gum Arabic Archaeologists have found 6000-year-old ceramic vessels that had broken and been repaired using plant resin. Most early adhesives were animal glues made by rendering animal products. Native Americans use of buffalo hooves Hide glue Bone glue Fish glue Rabbit skin glue

15 History--cont. Native Americans in what is now the eastern United States used a mixture of spruce gum and fat as adhesives and as caulk to waterproof seams in their birch bark canoes. During the times of Babylonia, tar-like glue was used for gluing statues. Egypt was one of the most prominent users of adhesives. The Egyptians used animal glues to adhere tombs, furniture, ivory, and papyrus. Mongols used adhesives to make their short bows. In Europe in the Middle Ages, egg whites were used to decorate parchments with gold leaves. In the 1700s, the first glue factory was founded in Holland, which manufactured hide glue. In the 1750s, the British introduced fish glue. As the modernization continued, new patents were issued by using rubber, bones, starch, fish, and casein.

16 Adhesive/Glue Terms Pot time The amount of time that can elapse between when the adhesive is exposed/mixed until the reaction develops to the point that the adhesive will not produce a good joint. Movement of the joint during this time should not reduce the strength of the joint. Varies with the type of adhesive and the environment. Set time Starts with the assembly of the joint. Any stress applied to the joint during this time will reduce the strength of the joint. For some adhesives it is the amount of time pressure should be held on the joint. Cure time The amount of time before the adhesive reaches maximum strength. Varies with the type of adhesive an the environment

17 Disadvantages of Adhesive Bonding Advantages No stress concentrations due to piercing of the adherend Improved fatigue resistance Lighter weight structures Ability to join and seal simultaneously Ability to join shock-sensitive substrates Can be less expensive than mechanical fasteners Disadvantages Strength is dependent upon the condition of the adherend surface Limited non destructive quality control methods Can be more expensive Bond quality is dependent upon many variables No single universal adhesive for all applications Limited disassembly and repair Process can be easily automated

18 Categories of Adhesives Structural Natural Synthetic adhesives Thermoplastic adhesives Thermosetting Pressure sensitive Structural adhesives harden by one of four (4) methods: 1. Evaporation of a solvent or water (white glue), 2. Reaction with radiation (dental adhesives), 3. Chemical reaction (two part epoxy) 4. Cooling (hot melt) Pressure sensitive adhesives (PSA s) form a bond simply by the application of light pressure to marry the adhesive with the adherend. Pressure sensitive adhesives are designed with a balance between flow and resistance to flow. PSA s are designed for either permanent or removable applications

19 Natural Adhesives Generally set by solvent evaporation. They are generally of low strength and are susceptible to moisture and mold. Their use is restricted to the joining of low strength materials. Type Notes Fish Animal Casein Vegetable Improved temperature resistance, resistance to water compared to above Made from collagen, (Skin/bone) with sugar and glycerol added for flexibility. Supplied as powder/bead which is dissolved in water Made from milk precipitated with acid. Supplied a powder for mixing with water. Improved properties compared to all above glues Based on starch, dextrine. Supplied as a powder for mixing with water. Low strength. Low resistance to water/high temps

20 Synthetic Adhesives Elastomers Based on natural and synthetic rubbers set by solvent evaporation or heat curing. They have relatively low shear strength and suffer from creep and are therefore used for unstressed joints. They are useful for flexible bonds with plastics and rubbers. Natural Rubber Polychloroprene Polyurethene Silicone Rubber Rubber solution with bonding be evaporation of solvent. Not suitable for loaded structures or adverse environments. Good for water but low resistance to oils and solvents (Neoprene) Two component adhesives which can be formulated for applications. Resistant to acids, oils some solvents and alkalis. Susceptible to moisture. Load bearing duties viable. Flexible bonds suitable for shock and vibratory loading. High strength joints Set at room temperatures. Has a high temperature service temperature of up to 300 o C. Low shear strength. Very good sealing /space filling adhesive - widely used for glazing

21 Thermoplastic Adhesives Fusible Soluble Poor heat and creep resistant. They are Supplied normally as an emulsion used in water, for for porous low/medium materials, especially wood Shear strength is good loads. Resistant to oil Polyvinyl Acetate (PVA) Poor resistance to water Low heat tolerance ( White glue) They have good resistance to oils but poor Harden quickly in seconds based on catalytic action of surface moisture. resistance Good to for rubber. water. Cyanoacrylates Care needed when used with metals in moist warm conditions. "Superglue"

22 Thermo Setting Adhesives Set as a result of the build up of molecular chains to produce a rigid cross linked structure. Type Info Resorcinol resins Polyesters (unsaturated) Polyamides Epoxy resins Good water resistance. Used for exterior plywood. Usually made to harden by chemical action rather than by the evaporation of solvents and thus cure with little shrinkage. High performance adhesives requiring higher curing temperatures and bonding pressures (up to 0.7 MPa ). High cost adhesive. Epoxy (mostly 2-part) adhesives have good strength and chemical resistance, do not produce volatiles during curing, and have low shrinkage. Form extremely strong and durable bonds with most materials in well-designed joints. Single part adhesives require heat for setting or long setting times.

23 Using Adhesives Select the best adhesive for the materials being used and the environment. Follow manufacturers instructions. Prepare joint Clean Close fitting Dampen Apply adhesive Uniform layer Some suggest using a notched applicator. Insure joint has sufficient adhesive to form a squeeze line when the joint is clamped. No squeeze line = insufficient adhesive (starved joint) Excessive adhesive squeezing out = wasted adhesive

24 Using Adhesives--cont. Force surfaces together Use correct amount of pressure Insufficient pressure will result in a poor joint Excessive pressure may reduce joint strength Clamps Nails or other fasteners

25 Adhesive Failure Adhesives can fail at several different points. Common failures are: Cohesive Adhesive (Interfacial) Mixed fracture Alternating crack path