Injection mold rapid prototyping RP

Traditional manufacturing strategy is to scale first, in the 1980s raised the price and quality of the first, since the nineties, has been developed for the market response to the first. In manufacturing increasingly international situation, shorten product development cycles and reduce investment risks to develop new products, to become the key to business survival. In recent years, the manufacture manufacturing market is undergoing strategic focus from cost and quality time with the response to a major shift. Quickly diversified manufacturer of products to market is to grasp market opportunities and an important guarantee of survival, rapid response manufacturing has become an international research focus, came into being in rapid prototyping / rapid tooling / Rapid Manufacturing technologies for enterprises to improve Competitiveness provides an advanced means. The technology is based on forming a high-tech material accumulated manufacturing technology, is considered the 20th century, a revolutionary breakthrough in the field of manufacturing, can manufacturing injection mold, die casting mold, stamping mold and other types of sophisticated mold, has been used in wide range automotive, aerospace, shipbuilding, home appliances, industrial design, medical, construction, crafts and children’s toys and other fields, and with the technology itself continues to evolve and improve, will continue to expand its wide range of applications.

In the automotive, appliance manufacturing, mold forming parts manufacturing hours accounted for 50% to 70%. Mold manufacturing is restricting our cars, home appliances, light industry and key bottleneck in the development, with the rapid prototyping and rapid prototyping hardware and software development and improvement of materials, rapid prototyping parts of the strength and precision has been continually improved, rapid prototyping technology has been gradually deep into the field of rapid tooling, rapid prototyping method based on simple rapid economic mold manufacturing various types of RP & M applications has become a hot issue.
A mold rapid manufacturing

Although the advent of rapid prototyping technology is not long, but because it makes the manufacturing of the enormous benefits of this technology has been used widely, especially for mold design and manufacturing to bring a leap. Rapid prototyping technology can accurately produce the mold core and cavity, can also be used directly in the process of making plastic injection sample in order to detect and correct errors. Due to the rapid prototyping applications of this new technology, design and manufacture of the mold gradually tends to digital, fast, thus enabling mold to shorten cycle and reduce costs in the process, greatly step forward.

Rapid tooling rapid prototyping techniques are mostly based on the production of physical models that kind of mold (master) using the copy mode (such as metal spraying, plating, composite casting, casting, etc.) to quickly manufacture of molds main working parts (convex and concave mold or in the cavity, the mold core), and its manufacturing cycle is generally conventional cutting method NC 1/5 ~ 1/10, while the costs are only the 1/3 to 1/5.

The mold materials, production costs, RP prototype materials, production batch, the mold has developed a variety of precision process method. The current rapid tooling methods generally have indirect and direct molding molding method, based on RP rapid manufacturing mold molding method mostly indirect method. Based on different materials, indirect method produced molding mold has soft mode, bridge plastic box mode and hard mode. Soft mold (soft tooling) generally refers to a silicon rubber mold. With SLA, FDM, LOM or SLS technology to produce such a prototype, and then translated into silicone rubber mold, the mold filling two-component polyurethane, is obtained after curing of parts required. Bridge module (bridge tooling) usually refers to the injection can be directly produced by the mold resin. Conventional epoxy resin mold and injection mold cost compared to only a fraction of the conventional method, the production cycle is greatly reduced. Less steel die life, but better than silicone mold, up to 1000 to 5000 to meet the needs of small and medium batch production. Die (hard tooling) usually refers to the steel mold, which uses indirect manufacturing metal molds and direct processing of rapid prototyping using metal molds. This article from China Hot Mould Network

Rapid tooling molding cycle is short, simple process, easy to spread, low cost tooling, precision and longevity to meet the functional needs of a specific, comprehensive and good economic benefits, is a fast, convenient and practical mold manufacturing technology, especially for new product development, prototyping, process validation and functional verification, and plastic packaging many varieties of small batch production.

Increasing competition among enterprises, increasingly demanding shorter product development cycles for rapid tooling technology provides opportunities and development space. With the development of industrial production, rapid tooling technology more and more product developers and mold industry wide attention, the research is in the ascendant, the new technological achievements continue to emerge, showing a vibrant trends, has great vitality.

Second, rapid injection molding manufacturing technology – metal spraying molding method

1, metal molding method Introduction

Metal spraying molding method is rapid prototyping and thermal spraying, rapid solidification methods such as the combination of indirect molding method, the process is molten or semi-molten metal plastic case particles sprayed through the SLA, SLS or LOM prototype manufactured packaging company by the method, generate metal thin layer, and then reinforcing backing and mold products obtained after removal of the prototype. There are two forms, namely atomization spraying method (rapid solidification process RSP), a spray coating method. When the mold is required life of 3000 or less, the general use of the RP prototype for the mother mold, the molten low melting point metal (such as zinc-aluminum alloy) with a sufficient rate of the atomized spray to the surface of the female mold, the mold is formed cavity surface, filling composite backing, making zinc-aluminum alloy soft molds.

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Metal spraying mold molding method as a standard sample, the mold cavity dimensions, geometric accuracy depends entirely on the kind of mold cavity surface and the formation of fine patterns at once, so the molding speed, short manufacturing cycle, mold, long life, cost low, only numerical method to process steel 1/3-1/5. Mold surface finish is good, simple process, low equipment requirements, more suitable for injection molding, die casting, sheet metal rolling die rapid manufacturing.

2, metal molding method step

Metal spraying molding process can be divided into five steps:

(1) model preparation

Models can be made from many materials, including plastics, plaster, rubber, wood and so on. First, a three-dimensional model, and then slicing them by mold-like mechanism for rapid prototyping. Model preparation is the most important model for surface cleaning and painting release agent.

(2) metal spraying model

After drying, mold release agents, choose the best spray parameters, you can start spraying the metal in the mold, spray gun should ensure that continuous motion, to prevent overheating of deformation coating, the coating thickness can be controlled within 2 ~ 3mm.

(3) make the mold frame

If the mold in the work subject to the pressure or the mold must be installed on the work in the molding machine, the mold must have a skeleton made of skeleton structure and shall be provided with packing.

(4) filling of the mold casting material

The filling material should have high thermal conductivity and a low solidification shrinkage and high compressive strength and wear resistance. The filler material is usually selected epoxy resin and aluminum powder, aluminum metal powder mixture of particles. This article from China Hot Mould Network

(5) stripping and polishing the surface of the mold cavity

After stripping should remain in the metal mold release coating surface clean, then according to the different needs of the mold polishing postproduction.

(6) assembling tryout
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3, spraying equipment and spraying material

Metal arc spraying work system in general by spraying power, wire feeder, gun and compressed gases and other system components. XDP-5 type arc spray equipment is stable and reliable, easy maintenance, capable of heavy spraying work, the basic parameters are:

Power supply voltage: 380V
Rated input capacity: 12KVA
Rated current: 300A
Use compressed air pressure: 0.6Mpa
Compressed air consumption: 1.6 ~ 2m3/min
Wire feed speed: 0 ~ 4.8 m / min

For arc spraying molding materials, to meet the low plastic trays melting point, low shrinkage case, as far as possible with good mechanical properties and relatively dense coating microstructure. Currently available in the market with a wire arc spraying aluminum, zinc, copper, nickel, stainless steel, aluminum, bronze, babbitt, composite wire, and many other varieties. However, refractory metal, such as steel, nickel, copper and spraying the coating shrinkage, thermal stress, relatively large porosity, the coating easily cracking, warping, peeling, so that at present only a low melting point of zinc, aluminum timber suitable for mold making.

Three, metal injection molding technology for rapid manufacturing and development of application examples

Spraying metal molds particularly suitable for the production of reaction injection molding process in the production of the polyurethane components, are widely used in plastics processing in reaction injection molding, blow molding, structural foam injection molding, and other processes, such as can be used to produce automotive steering wheel, car dashboards, upholstery, head cushions, spoiler, automotive interior headliner, etc., can be used in light industry in the manufacture of polyurethane soles, compared to silicon metal spraying rapid tooling rubber rapid tooling longer life, can be applied in the injection molding machine for the production of small quantities of products. In the application of injection molding process should take into account the low melting point alloy metal spraying the mold cavity performance and life limit. To prevent premature damage to the mold, the injection pressure is not too high, but it must ensure that the products can be formed in the minimum injection pressure, or will cause injection of dissatisfaction. Other specific injection process parameters in Table 1.
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Metal spraying injection mold successful application examples:

1 pot injection mold base

If you use clamshell packaging the traditional method of EDM, which cost about 4,000 to 5,000 yuan, the production time is about a month or so, but with arc spraying rapid tooling methods to produce, it costs about 1,100 yuan, working hours 60h or so. This is exactly the arc spraying rapid tooling receive widespread recognition of the reasons.

Flowerpot base injection mold making manufacturing processes: machining spraying shell plate concave cavity preparation before spraying spraying Dies epoxy resin and aluminum metal shell configuration and filled epoxy plastic package curing master mold surface coating cleaning spray punch epoxy resin and aluminum metal shell configuration and filled epoxy curing convex and concave mold separation and cleaning the mold surface machining mold parts assembly tryout.

2 drip dripper rapid tooling with

National Center for drip irrigation emitters rapid tooling is used by making drippers RP model, using metal spraying zinc alloy molding method soft mold manufacturing, injection molding 1000 dripper products for agricultural water-saving irrigation experiment. National Irrigation center RP & M prototype for the mother mold used to clone drip dripper mold, rapid prototyping technology has played a superiority quickly achieve a new product trial, including RP prototypes, making the production cycle is only 2 weeks.

3, Idaho injection mold

Idaho National Engineering and Environmental Test Center using rapid clear plastic box solidification process that RSP technology to achieve rapid economic manufacture of plastic injection molds. This method produced using rapid prototyping technology as the parent sample template, the template by spraying to the parent metal or alloy droplet deposition manufacturing mold. This article from China Hot Mould Network plastics products

Process as follows: a molten tool steel or other alloy is pressed into the nozzle, and high-speed flow of inert gas meet and a diameter of about 0.05mm droplet mist, sprayed and deposited to the parent sample, the replication of the parent sample surface structure and shape, with the release agent to make deposits formed steel mold with the parent sample separation, can be quickly made the required mold.

Recently, Xi’an Jiaotong University School of Mechanical Engineering, Institute of Advanced Manufacturing Technology used successfully “arc spraying and brush plating integrated mold manufacturing technology” for the development of new models of cars large stamping dies rapid manufacturing, the technology packaging design integrates rapid prototyping, arc spraying and electric plating technology, the use of electric arc spraying female mold surface of the mold rapidly deposited a dense low melting point metal shell, thus creating a mold cavity; the filling suitable backing material and the release, the use of the brush plating technology in mold strengthening the work surface plating coating, and then complete the mold rapid manufacturing.

Use of the technology and equipment, combined with rapid prototyping technology and high-speed CNC machining technology, cost-efficient large-scale, sophisticated, complex and long-life molds rapid manufacturing.

Using electric arc spraying and brush integrated mold manufacturing techniques cover mold, costs only traditional machining steel molds 1/10, the manufacturing cycle for the latter 1/4 to 1/5, very substantial economic benefits, very suitable in the development of new models in the kind of car prototype and small batch production. The technology can also be used to injection mold rapid manufacturing.
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