They have introduced magnification factor q which give more accurate prediction of total allowable deflection and strain value for short beams. The snap fit design program is a webbased application that serves as an engineering tool in snap fit design. It discusses snap fit mechanisms, locators, locating schemes and overconstraints, designforassembly, and the snapfit function from the end user pointofview. The cantilever is the most common snap fit joint and consists of a protrusion some type of bead or hook at one end of the beam and a structural support usually a cutout at the other end. If you are looking for a calculator, this one might help you. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Running interference manufacturing automation and design. Also known as a force fit or interference fit, a press fit is an assembly in which one part is inserted tightly into a hole in another part. This uses less material and results in a more even distribution of strain in the cantilever. Snap fit design by neeraj kumar jha linkedin slideshare. May 08, 2017 for a more indepth analysis of snap fit design and to dive deeper into the material properties, check out these guides below. Contains the engineering formulas and worked examples showing how to design snapfit joints for bayer thermoplastic resins. A snapfit cantilever with constant cross section has an uneven distribution of strain top image. Most snapfit joints have a common design of a protruding edge and a snapin area.
Snap fit design snap fits are commonly used as an assembly method for injection molded parts. Procedia cirp 50 2016 264 a 269 b slot to avoid undercut c snapfit placed on edge slotundercut a tooling with slider required fig. Basf is now one of the largest plastics producers worldwide and has an extensive range of styrenebased products, polyurethanes, and engineering plastics. Its fun, creative, artistic and constructive and helps kids. Apr 01, 2014 snap fit assemblies also require more engineering calculations and analysis. A continuous annular snap joint offers a semihermetic seal and is better for single assembly applications a page 6 of 26 snapfit joints for plastics a design guide. The snapfit design workspace program includes the deflection magnification factor q factor in all cantilever calculations see uniform beam q factor and tapered beam q factor diagrams. As the hook passes the edge of the hole, the cantilever beam returns to its original shape. Designing components with snap fits can save you time and money in production by reducing material costs and part quantities as well as improving ease of assembly. Or is there some functionality within solidworks itself to design snaps.
The program provides a workspace for the designer to test different scenarios by adjusting various input parameters and selecting different engineering materials for the snapfit design. The program provides a workspace for the designer to test different scenarios by adjusting various input parameters and selecting different engineering materials for the snap fit design. When snapfit joints are being designed, it is important. For a more indepth analysis of snap fit design and to dive deeper into the material properties, check out these guides below. The assembly stays in place through friction and the force of the two parts pushing against each other. April 2009 1 preface this set of hints and tips for plastics product designers is intended as a source book and an aide memoire for good design ideas and practices. Computational models to facilitate the contact analysis are provided. Snapfit assemblies also require more engineering calculations and analysis. I am working on a part that was originally designed to use lexan pc. Whether the snap joint is a cantilever or a cylindrical fit, they both function similarly. The first snapfit handbook creating and managing attachments for plastic parts 2nd edition paul r. Design guidelines for additive manufactured snapfit. I have seen through this forum that most people recommend pom acetal copolymer for this application. However, on a permanent snap fit there is no lever or pin.
Contains the engineering formulas and worked examples showing how to design snap fit joints for bayer thermoplastic resins. The specific name of the snapfit is usually named after the type of stress or strain it utilizes. Threaded connections, such as bolts and nuts, are used in a wide variety of applications, ranging from plastic toys to massive bridges. Designing of plastic products for injection moulding. Pdf design guidelines for additive manufactured snapfit joints. Threaded locking methods for secure connections fictiv. Plastic snap fit design plastic snap fit design miner00 mechanical op 9 nov 01 11. Snap fit latch design a snap fit latch is the simplest, quickest, and most costeffective method of assembling two or more parts. Snapfit integral attachments are used widely for joining plastic parts. Snap fits all snap fits are variations of two basic. I am having issues with the snap fitting design as i have no experience in this field. Most of these plastic model kits feature snap construction in which no gluing is required. This book is a very good reference for designing plastic snapfit features. One of the most common causes of snapfit failure is stress concentration at the sharp inside corner between the beam and wall to which it is attached.
Snapfit and diecast plastic model kits, balsa kits, vac. I have not determined the material yet, however when i 3d printed a previous design in abs with larger snap fitting than the attached it didnt fit and broke from the fitting force. The force to assemble and disassemble snap fit assemblies is highly dependent on the overhang entrance and retraction angles. The torsion snap can be released by pressing this design can be used for frequently assembled and disassembled parts, or to provide constant pressure to the assembly. This uses less material and results in a more even distribution of strain in.
Torsion snapfit springloaded lever that snaps into place when the mating part is pressed into place. Snap fit joints are also relatively easy to assemble and disassemble. Cylindrical snapfit joints are commonly used for connections and fastening typical questions what is the maximum assembly force for a given snapfit design. The force equations for maximum strain are independent of q which is basically a modifier to include the stiffness of the base of the beam in. Torsion snap joint on a housing made of makrolon polycarbonate fig 6. Most of the plastic model kits come molded in color but you can choose to paint them if you like. Seminar 1 presentation on snap fit design preparedby. It is difficult to design snap fits with hermetic seals. Currently, there is a formula to determine the strain factor and i usually work to this differences occur depending upon the plastic used of course and not exceed the percentage figure 6% in most plastics. One of the most common causes of snap fit failure is stress concentration at the sharp inside corner between the beam and wall to which it is attached.
Shape memory polymer actuated hollow snapfit design analysis article in materials and design 47. A snap fit cantilever with constant cross section has an uneven distribution of strain top image. Has anyone had any luck using polycarbonate in the design of plastic snap fit parts. The snap fit design workspace program includes the deflection magnification factor q factor in all cantilever calculations see uniform beam q factor and tapered beam q factor diagrams. It discusses snap fit mechanisms, locators, locating schemes and overconstraints, design forassembly, and the snap fit function from the end user pointofview. Predicting and validating assembly forces of cylindrical. Dsm engineering plastics technical guidesnap fit designcantilever beam snapfitscantilever beam type snapfits can be calculated using a simplification of the general beam theory. There is a lot of types of snap fit but im planing to use a circular one do you know what are the parameters that should be respected to make a good. The proliferated use of integral attachment in the form of snapfit features in designs is due to the ability to mould such. In a typical snap fit, the strength of a beam is dependent on its geometry and maximum deflection during assembly. How to design snap fit components fictiv hardware guide. Anyone know of a simple snap fit design calculator. Jul 22, 2011 seminar 1 presentation on snap fit design preparedby.
To remain competitive, industry is continually searching for new methods to evolve their products. You can design the joint to be either detachable, difficult to disassemble, or inseparable, depending on the dimension of the insert and the return angle. Design guidelines for additive manufactured snapfit joints. Snap fit is formfitting joint which permits great design flexibility. Most all snapfit joint designs share the common design features of a protruding ledge and a snap foot. Jones, short cantilever beam deflection analysis applied to thermoplastic snapfit design, 1987 spe. Below is simple table for designing snapfit joints from bayer snapfit joints for plastics a design guide, please consult the pdf for more info. There is a lot of types of snapfit but im planing to use a circular one do you know what are the parameters that should be respected to make a good snap fit. How much do material property variations influence the results. It goes through a logical design sequence to create a snap fit design that works in. Virtually all consumers and industrial products, utilizing plastic molded components, have multiple components attached together with some form of snap fits. The snap fit design guide by basf 9 has designed snap fit calculator which utilizes all the beam formulas and calculates the stress or strain values induced by the deflection. Building model kits is a hobby kids can enjoy for a lifetime.
Pdf design guidelines for additive manufactured snapfit. Types of snap fit joints there are a wide range of snap fit joint designs. A systematic approach to integral snapfit attachment design. Insufficient or excessive mating forces would impair assembly quality. Jul 22, 2011 fusion 360 snap fit cases 3dprintable raspberry pi case duration. Traditional integral snap fit attachment design focuses almost exclusively on the individual locking features, such as cantilever hooks, bayonetfingers, compressive hooks and others. See more ideas about plastic design, design, 3d printing. Indeed, incorporating a press or snap fit into a design to take advantage of the speed and economies it allows labor reduction and elimination of assembly fixtures, equipment andor inventories of separate fastenersmay be one of the more critical decision points in a successful product. A multiple use snap fit usually has a lever or pin to be pushed, in order to undo the snap fit.
While in the past injection molding has been the only viable method for producing snap fit joints in plastics, 3d printing opens up new opportunities and challenges in their design. Annular snapfit joints cantilever snap joints torsion snapfit joints annular snapfit joints this is a convenient form of joint for axissymmetrical parts. This utilization of snap fit joints for plastic molded. The design of the snapfit determines what it can be used for. We will be using a cantilever snap fit joint for this part. As i understand your joint is c cross section with 1st type. Please practice handwashing and social distancing, and check out our resources for adapting to these times. New and highly efficient technologies and production processes combine with optimized production systems within a unique logistics structure, making basf products leaders in terms of both cost and technology in many sectors. Plastic snap design free download as powerpoint presentation. Snap fits work by using an undercut in one piece and, on the other, a lip or hook which snaps into the undercut. Im designing 2 objects that should be attached to each other and removed when its necessary. Sep 22, 2015 the proper knowledge of materials and its manufacturing process helps a designer to select the best material as per its application.
The cantilever snap fit is the most commonly used snap fit of the three. A good design tip is to diminish the cross section of cantilever beam over its length bottom image. Snapfit assembly cantilever snap joints are the most common typically, a semiflexible cantilevering hook is deflected slightly as it is inserted into a hole or past a latch plate. It includes formula for calculating all of the important functions i wanted to predict in a design. Fusion 360 snap fit cases 3dprintable raspberry pi case duration. Where can i find the design calculation of snap fit joint. Most all snap fit joint designs share the common design features of a protruding ledge and a snap foot. If you continue browsing the site, you agree to the use of cookies on this website. A cantilever snapfit latch basically consists of a protrusion some type of bead or hook at one end of the beam and a structural. A product of the bayer design engineering services group, this manual is primarily intended as a reference source for part designers and molding.
Snap fits are very useful because they eliminate screws, clips, adhesives, or other joining methods. Jun 03, 2015 i am having issues with the snap fitting design as i have no experience in this field. Design of a constantforce snapfit mechanism for minimal. In their basic form, the most often used are the cantilever beam snap leg, figure 1, and the cylindrical snap fit joint, figure 2. Nov 28, 2012 fundamentals of annular snap fit joints machine design stay safe and healthy.
Plastic snap fit design plastics engineering general. Although they have been around for many years, they have recently become more important in an attempt to simplify assembly and its associated costs. The new snapfits provide constant mating forces against interference uncertainty. Snap fit design using classical beam theory iii3 concluding points. Design and analysis of snap fit joint in plastic part. A continuous annular snap joint offers a semihermetic seal and is better for single assembly applications a page 6 of 26 snap fit joints for plastics a design guide. For example, the valve covers on an engine have to stay in place while driving, but we also need them to be. Shape memory polymer actuated hollow snapfit design analysis. Assembly is accomplished without the use of any additional components or fasteners.
A cantilever snap fit latch basically consists of a protrusion some type of bead or hook at one end of the beam and a structural. After a bit of research i learned that one way to do this is with snapfit joints. I have no mechanical engineering background so i didnt even know the relevant terminology. Snapfit latch design a snap fit latch is the simplest, quickest, and most costeffective method of assembling two or more parts.
The design normally features a straight snap fit but i want to incorporate a curve in the snap fit design. This calculation of maximum deflection of snap and mating force ref. How to design snapfit joints for 3d printing 3d hubs. Snapfit latch design a snapfit latch is the simplest, quickest, and most costeffective method of assembling two or more parts. In general, the stiffness of the part to which the snapfit connects, isimportant. Sep 01, 2017 section view of the completed snap fit features. You should also check for spherical joint clearance should be y2. Predicting and validating assembly forces of cylindrical snap. Use of snapfit fasteners in the multilifecycle design.
Oct 14, 2016 the design normally features a straight snap fit but i want to incorporate a curve in the snap fit design. Traditional integral snapfit attachment design focuses almost exclusively on the individual locking features, such as cantilever hooks, bayonetfingers, compressive hooks and others. If anyone can help me it would be greatly appreciated. A cantilever design can be multiple use or permanent.
Designing with l and u shaped snap fits request pdf. The tooling for the design in 4c is even simpler, because the designer can place the separation line of the tool along the edge of snapfit. Snapfit design workspace but if you are open to other tools in your snapfit design process, you might also be interested in this short live demo session on the application of 3d simul. The proper knowledge of materials and its manufacturing process helps a designer to select the best material as per its application. Snap fit is used to fix two parts together in a certain position. Snap fits all snap fits are variations of two basic designs, cylindrical fig. The one similarity that ties them together is that these connections need to stay together when we want them to, but also come apart when needed. Fundamentals of annular snapfit joints machine design. Highlights the mating forces of typical snapfits are sensitive to interference. Accordingly, the design of a snap fit joint is highly dependent on the polymeric materials. Scribd is the worlds largest social reading and publishing site. The snapfit design program is a webbased application that serves as an engineering tool in snapfit design. A key feature of snap fit joints is that the snap fit elements are integral constituents of the parts to be joined. How do closedform solutions compare to simulation results.