1. Fixture design
1.1 The definition of fixture
Generally speaking, fixture can be any auxiliary device which can make scientific molding process more quick, convenient and safer during the die manufacturing. Broadly speaking, fixtures include machine fixture, press fixture, heat treatment fixture, welding fixture, assembling fixture and so on. In a narrow sense, it is machine fixture. And it’s mainly used during the machine dies processing. At present, the general definition is that fixture is a device tool used for clamping die parts. And another definition is that he fixture or jig is a kit used for clamping the casting part and guiding the tool.
1.2 Types of dies fixture
There are two main types of die fixture, tooling fixture and testing fixture.
Metal casting manufacturers mainly use tooling fixture to satisfy their requirement of casting manufacturing process convenience and high level of precision. In a word, the tooling fixture should help to make die making process of metal punch machine work, welding and assembly be easy.
And die set manufacturers always use testing fixture for testing. Because there are many examples of die casting products which shapes are complex and dimensions are difficult to measure. In this case, we have to make the die design of special detection block. Or we design the testing fixture for particular metal casting products of detection use.
For example, punch press dies suppliers have some regular testing fixtures for metal dies, such as plug gauge, ring gauge and so on. However, there are also many irregular machine dies, for which punches and dies engineering people have to make special forming die design. What’s more, we press die manufacturer may use some machine metal casting methods to ensure the precision of the testing fixture. Such as wire cutting, spark-erosion machining, CNC machining center and so on.
2. Principles for fixture design
2.1 Fixture usage
In some special metal casting process scenes, we need to make fixtures to facilitate and serve our die production. There are these main using scenes.
2.1.1 Using fixtures to fix products and tools
Die set manufacturers always fix die casting products and tools with fixed vise and clamps. It can release a hand of operators with metal casting techniques, and then they can work with both of their two hands.
2.1.2 Using special tools
Tooling we use on the die production line should be best fit for this forming die and special tools for manual operation. And the aim of this operation is to increase the die production efficiency.
2.1.3 Merging the two different types of dies tools into one
As die casting parts manufacturers all know, this operation can reduce the trouble of changing metal casting tools and the labor hour consumption for transfer. Therefore, it can significantly increase the working efficiency of die casting parts manufacturers. One featured application is a pencil with an eraser on the top.
2.1.4 Improving die casting tooling design convenience
Firstly, punch press dies suppliers design the die casting tooling handle to make it easy to grasp. Secondly, the operating die casting tools are in harmony with human movements. Thirdly, punch dies suppliers should evaluate the fixture with IE method.
2.1.5 Operation process
Firstly, as large steel castings manufacturers all know, the operating position should be close and focused. Secondly, we should try to make the die making machine minimize or even disengage human’s monitoring and assistance. Thirdly, punch and die manufacturers need to take the switch position and the next process into account. The start switch position of the die press machine and the operation of the next mold casting process should be coherently coordinated in the action.
Fourthly, it’s about the auto uncaging of parts of die. We try our best to make the finished die cut parts automatically fall off by means of gravity or springing.Last but not least, we use self-checking automation system, and put safe first.
2.2 Design principles
There are different fixture design principles for different conditions.
2.2.1 Measuring and auxiliary positioning fixture design
A.Make the shape of fixture be simple and die making process be convenient.
B.It’s easy to pick and place die casting products.
C.Ensure the position of the fixture and metal casting products to be accurate.
D.Learn the measurement key point and measurement methods of metal molds.
E.In general, the material used in dies fixture measurement is aluminum alloy. And when the precision requirement is higher, press die manufacturer uses steel mold.
2.2.2 Position fixture design
As for assembly positioning fixture, die manufacturers should protect it by teflon tape. And reserving 0.2-0.3mm position on one side to avoid scratches of die casting products.
The metal die position should be accurate, and not be too loose. The standard is to make the pick and place of metal punch dies be easy.
Die casting manufacturers reserve about 0.1-0.2mm gap on one side when they put protective film and locate the fixture. If the dimension of press dies is small, we can consider to reduce the gap within 0.1mm.
With regard to gloss positioning fixture, die casting supplier reserves about 0.2mm. And the standard is also to make the pick and place of metal punch dies be easy. If it’s gloss machine fixture, the reservation gap should be about 0.1mm. Certainly, the aim is to avoid the drop of forming die in the wipe process because it is too loose.
With respect to printing and laser carving tools, metal stamping die manufacturers reserve 0.05-0.1mm gap. The support surface at the printing position and the positioning of the laser engraving fixture needs to be precise.
2.2.3 Coating fixture design
Punch and die manufacturer should know the spray printing range of mold die and the paint types.
It should be easy to pick and place of thermoformed products on the fixture.
When the precision requirement of mold coating products is pretty high, the die mould manufacturer need to adjust the tolerance on fixture design.
Die set manufacturers need to think about the lacquer flying area and painting accumulation problem. What’s more, there are die making process problems of gas pattern, solvent evaporation marks, sawtooth and so on.
Pay attention to the coating method during metal moulding process. For example, rotary machine, reciprocating machine, hand painting, water electroplating, vacuum plating and so on.
3. Common thermoforming material used for fixtures
3.1 Rolled Steel
There are many different types of hot rolled steel, and the applications of rolled steel products are diverse. According to the different shape of cross section, the steel can be divided into four main types. Steel rolled sections, hot rolled steel plate, hot rolled steel tube and rolled metal products. The rolled steel is made from ingots and billets by pressure casting. It can be different shapes, dimensions and casting properties.
3.1.1 45# steel
Chemical components of 45# steel includes these. The carbon content is 0.42-0.50%, the silicone content is 0.17-0.37% and the manganese content is 0.50-0.80%. What’s more, the chrome content is within 0.25%, the nickel content is within 0.30#, and the copper content is within 0.25%. Also, the density of hot rolled steel 45# is about 7.85g/cm3,, and its hardness is about 45-52HRC. In addition, according to the different shape, we divide the roll formed steel 45# into hot rolled steel sheet, rolled steel tube, and hot rolled steel bar.
SKD11 is a kind of hot rolled alloy steel with high content of carbon and chrome. And it has a high hardness and good wear resistance. What’s more, this hot rolled steel properties include strong hardenability and good dimension stability. Therefore, it’s suitable for making cold steel die with high precision and long lifetime, and mold die of thermosetting plastic products.
Properties of hot rolled steel SKD11 are as follows. Firstly, it has good toughness and high temperature fatigue resistance. Secondly, this rolling steel can withstand temperature fusion, ands is suitable for long-term work at high temperatures. Thirdly, it has good cutting performance and polishing performance.
What’s more, the application of hot steel SKD11 is diverse. For example, cutting die, stamping die, thread rolling die, wear-resistant sliding block mould, thermosetting resin forming die, and so on. The hardness of them can be 56-58 HRC. What we commonly see are sheet metal die and metal bar mold.
D2 rolling steel is a kind of high wear resistant cold rolled steel and tool steel with micro deformation. The carbon content is up to 1.5%, and the chrome content is up to 11.5%. After the hot finishing process, its hardness can be up to 60HRC. Its application includes metal stamping die, drawing die, stainless steel die, reeling die, metal parts production, machinery manufacturing and so on.
3.1.4 Other rolled steel
Besides for the above steel, the common hot steel we usually use to make fixture and compound die are CR12, tungsten steel, stainless steel, spring steels, SPCC、SUS、SK7、SK5 and so on.
PF is the acronym of phenolic resin. In general, it has several colors including orange, black, yellow and brown. PF is an insulation switch and variable resistor for electronic products, a mold die for machinery, and a fixture on a production line. Because it has properties of insulation, static electricity, wear resistance and high temperature resistance. What’s more, the PF can be used in transformer oil. The common thickness of PF is 3-50mm, and its common shape is plate.
PE plate is also known as high density polyethylene. It’s a kind of non-polar thermoplastic resin with high crystallinity. And the PE sheet is translucent to a certain degree in the thin section. As for properties, it has excellent resistance to most of the life and industrial chemicals. Firstly, the polymer is non-hygroscopic and has good vapor resistance. Therefore, it can be used for packaging applications. Secondly, it has good chemical stability, and can resist the erosion of most acids, alkalis, organic solutions and hot water. Thirdly, it also has good electrical insulation. Commonly, they are white or black, and their main shape are sheet and bar.
Acrylic is a kind of chemical material, which chemical name is PMMA and belongs to propylene alcohol. In the application industry, acrylic raw materials generally appear in the form of particles, plates, pipes, etc. Acrylic, also known as special treatment of organic glass, is a special generation of organic glass products. Its common colors are transparent and white, the thickness ranges from 1mm to 50mm, and its average hardness is 89 HRC. In addition to acrylic, common plastic materials we usually use to produce fixtures are ABS plastic, PS, PP plastic and so on.
4. Common fabricating machinery
Xu Zhuo Industrial Co., Ltd. is a professional fixture manufacturer. As early as 2010, it has a variety of fixture production equipment. Including ordinary lathes, numerical control lathes, milling machine, CNC, grinding machine, drilling machine, discharge machine, wire cutting machine and so on. We not only produce fixture and mould die for our plastic parts and silicone products, but also sale them to many famous clients. And we have advanced and practical model room. Therefore, our mould and fixture enjoy a high reputation in Dongguan, China.