what is snap fit design

Full Answer

What are the three types of snap-fits?

There are three main types of snap-fits: annular, cantilever, and torsional. Most snap-fit joints have a common design of a protruding edge and a snap-in area. The specific name of the snap-fit is usually named after the type of stress or strain it utilizes; the torsional snap-fit uses torque to hold parts in place.

What are the advantages of snap fitting?

Benefits of Snap-Fit Connections Can be designed right into the molding process, eliminating assembly steps and speeding up assembly and throughput. Reduces material needs, saves on material costs, and makes the product lighter weight.

What are snap-fit joints used for?

Snap-fit joints are especially useful in injection molding and additive manufacturing because of the flexibility they provide during the assembly and disassembly processes.

How snap-fits are made?

In its simplest form, a snap-fit is a small protrusion — a male component (hook, bead, or bump) that is deflected during assembly to catch in a female component (a depression) on the mating part. The shapes of the male and female parts determine whether the joint can be separated and the force required to do so.

How do you design a snap?

Taper the designFillet the base of the cantilever: Adding a fillet at the base of a cantilever will help distribute stress over a broader area, resulting in a stronger connection between snap-fit components. ... Increase the width: ... Deflect during assembly: ... Consider build direction: ... Add lugs:

How do I improve my snap-fit design?

A designer can increase the beam's rigidity by using either a higher modulus material or a thicker cross section. The product of these two parameters determines total rigidity of a given beam length. Increasing the overhang depth can also improve the integrity of assembly.

Are snap fits wood?

As mentioned before most snap-fit joints are found in plastic parts, because of the elasticity of this material. Snap-fits are also found in parts made from other materials like wood [10] or metal [4] but are less common.

Can you snap-fit metal?

Snap fits in metals are most common with spring tempered materials such as high carbon or alloy steels, strain hardened stainless steels, beryllium-copper alloys, and the like.

What is the difference between joints and fittings?

PIPE JOINTS Pipes are connected with the help of joints. A variety of joints are used in an assembly of pipes. Connecting two or more pipes together is called a fitting. Various types of joints could be used in a pipe as per the requirement.

Why is it called a snap?

The player snapping the ball (known officially as the "snapper" in rule books) delivers the ball to another player, and that action is the snap.

What are the two types of snaps?

There are two different types of snaps currently in the market, post-style and prong-style. A post-style snap has a shaft that requires a hole to penetrate the fabric. A prong-style snap has teeth that penetrate through the fabric.

Where is the most stress on a snap fit?

The worst case stress and strain is found at the root of the cantilever and can be easily approximated using classical beam bending theory. As the exact forces are not yet known when designing a model, it's most common to use deflection and strain rather than force and stress values to set your dimensions.

What are the advantages of snap fitting quizlet?

Advantages of snap fitting include (1) the method is fast, (2) no tooling is required, and (3) the parts can be designed with self-aligning features for ease of mating. What is the difference between industrial stitching and stapling? In stitching the U-shaped fasteners are formed during the assembly process.

What are the advantages and disadvantages of threaded joints?

Advantages of threaded jointsThey are reliable.Less force is required to tight a joint because of the mechanical advantage offered by spanner.They have small overall dimensions and are compact in construction.Threads have self-locking property hence they can be used in any position either vertical or horizontal.More items...•

What is the advantage of mechanical fasteners?

Here are a few advantages of mechanical fasteners: Manual, in-die or robotic installation is possible. Overall weight reduction is typically achieved. Minimum space requirements are needed within the tool.

What are the disadvantages of using the plastic snap together toy?

Question 6- A disadvantage of using the snap together toy to model compounds may be that they don't actually show the real item, the size or shape of the compound.

What is Snap Fit Joint?

A snap fit joint consists of a protrusion in a flex plastic wall. When force is applied, the flex part gets deflected and goes inside the depression during assembly with the mating part.

How does a cantilever snap work?

During snap design calculations, maximum snap deflection corresponding to allowable strain in the cantilever beam is calculated using beam theory.

How does a snap joint work?

One end of the cantilever snap joint is fixed. Whereas the other end is protruded out. They work similar to the cantilever beams. When the force is applied to the joint, flexible length deflects and catches in the depression of the mating part. During deflection maximum stress acts at the root of the joint.

What is the force required to engage a snap joint?

Snap mating force is the force required to engage the snap joint. Mathematically it is equal to the multiple of snap deflection force and frictional force.

What is an annular snap joint?

The annular snap joint is used to join symmetrical round parts. Depending on annular joint geometry, joints can be removable, permanent, or difficult to remove. Complex plastic tooling is required to make parts with annular snap joints.

What are the advantages of snap joints?

Plastic snap joints have the following advantages compared to other types of joints used in plastic parts. Simple and reliable. Improved Aesthetics: The product looks clean because fasteners are not visible from the outside. Reduced number of parts: No additional fastener such as a screw is not required.

How much does a cantilever beam thickness decrease?

Cantilever beam thickness is reduced gradually (up to 50%) from the root to the top of the cantilever snap to increase snap deflection or reduce stress on cantilever snap.

How does a torsional snap fit work?

Similarly to Cantilever snap fits, in a torsional snap fit one must deflect, or force the protruding edges of piece B away from the insertion area. Piece A then slides in between the protruding edges until the desired distance is reached. The edges of piece B is then released and piece A is held in place. The snap-fits in this description are the protruding edges of piece B. These types of snap-fits may have a spring in place; so that when activated, the locked in piece is released and put into action.

What is a snap fastener?

Metal snap fasteners, spring clips, and other snap-type connectors are still in broad use today. With the development of new flexible yet springy materials, such as molded plastic, and new manufacturing processes, many new variations in these types of connectors have been invented, and are commonly called snap-fits.

What is annular snap fit?

The annular snap-fit utilizes hoop-strain to hold into place. Hoop-strain is the expansion of the circumference of the more elastic piece as it is pushed onto the more rigid piece. In most cases the design is circular. Some popular examples are pen caps, ball and socket joints, snap fasteners and some water bottle caps. This kind of snap-fit can be used multiple times. However, permanent strain may develop, loosening the joint when it is used too often.

What is the oldest snap-together connector?

History. Snap-together connectors have been used for thousands of years. The first ones were metal. Some of the oldest snap-fits found are snap fasteners, or buttons , shown on the Chinese Terracotta Army featuring soldiers from the late Warring States Period.

What is snap fit?

A snap-fit is an assembly method used to attach flexible parts, usually plastic, to form the final product by pushing the parts' interlocking components together. There are a number of variations in snap-fits, including cantilever, torsional and annular.

Why are snap fit costs so high?

The high production costs are due to the amount of calculation and precision that must be done in order to create a strong snap-fit. Another reason is the creation of molds; they are more time-consuming from the integration of parts in the product.

What are the different types of snap-fits?

There are three main types of snap-fits: annular, cantilever, and torsional. Most snap-fit joints have a common design of a protruding edge and a snap-in area. The specific name of the snap-fit is usually named after the type of stress or strain it utilizes; the torsional snap-fit uses torque to hold parts in place.

How to find strain in elasticity?

So strain = stress / modulus of elasticity = change in length / initial length [%]

What to do if cantilever is too high?

If you’ve calculated your dimensions, chosen your material, and the acceptable strain rate is still too high, the best solution is to change the cantilever cross section. The most common changes include tapering the width or thickness.

What forces are used to set dimensions?

As the exact forces are not yet known when designing a model, it’s most common to use deflection and strain rather than force and stress values to set your dimensions. In other words, your dimensions will be limited by maximum strain during deflection rather than force required to assemble/disassemble (mating force).

Where is the worst case of stress and strain found?

The worst case stress and strain is found at the root of the cantilever and can be easily approximated using classical beam bending theory. As the exact forces are not yet known when designing a model, it’s most common to use deflection and strain rather than force and stress values to set your dimensions.

What is the Q factor in beam bending?

However, the part walls are likely to be of similar thickness to the cantilever itself; Q is the deflection magnification factor added to account for this.

What is a snap fit?

In its simplest form, a snap fit is a small protrusion (hook, bead, or bump) which is deflected during assembly to catch in a depression on the mating part.

Why do we need snap fits?

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.

What is prototyping plastic?

Prototyping plastics are ideal for design confirmation but are typically lower in strength than SLS or Material Jetting materials and are not suited for applications where the connection will be opened and closed repeatedly. Enclosure design for 3D printing: A step-by-step guide.

What is a cantilever joint?

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 at the other end. This protrusion is inserted into a cut-out or slot and deflects upon insertion.

What is an annular snap fit?

The annular snap-fit utilizes hoop-strain to hold a pressed part in place. Common examples of annular snap-fits are bottle and pen caps. Annular snap-fits are commonly used for the caps of pens. With annular snap-fits, it is possible to achieve a waterproof seal around the joint.

What is SLA resin?

SLA resins can be used for snap-fits, but are relatively brittle increasing the likelihood of breaking after repeated use. Durable SLA resin is recommended. SLS. SLS is suitable for printing functional snap-fit prototypes or end use parts that will be opened and closed many times.

What material is good for snap fit?

Good strength and elasticity combined with high resolution details makes Material Jetting good for snap-fit applications. Durable resin (PP-like) and Digital ABS are the most common materials for snap-fits because of their toughness and flexibility. Binder Jetting. Not suited for snap-fit connections.

What is a good design tip for a cantilever?

A good design tip is to diminish the cross section of cantilever beam over its length (bottom image ). This uses less material and results in a more even distribution of strain in the cantilever.

What is the tolerance for FDM?

For FDM a tolerance of 0.5 mm is recommended, and a tolerance of 0.3 mm best for all other 3D printing processes.