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Car Rearview Mirror Holder MIM Parts

Introduction of MIM Automobile Rearview Mirror Mirror Holder Parts

Car rearview mirror holder MIM parts
Item	Material	Production Process		Sintering Temperature		Mold	Custom
Rearview mirror mount	304 stainless steel	Metal Injection Molding		1550℃		To be customized	Yes
Chemical Composition	SUS 304: Requirements, % C:≤0.08 Mn≤2.00 P:≤0.045 S:≤0.030 Si:≤1.00 Cr: 18.0–20.0 Ni: 8.0-10.5
Available Materials	Low carbon stainless steel, titanium alloy (Ti, TC4), copper alloy, tungsten alloy, cemented carbide, high temperature alloy (718, 713)
Finish	Dimensional Accuracy		Product Density		Appearance Treatment			Appropriate Weight
Roughness 1～5μm	（±0.1%～±0.5%）		95～100%		Mirror Reflection			0.03g～400g）

Rearview Mirror

Typical structure, ingenious mold structure

Ingenious design, mold classic

The mold structure is like a game of chess. There is no same game through the ages. Each set of molds is different, and the mold structure is ever-changing. Especially for some complex molds, automobile molds, the structure is very classic. For mold people, they are happy to see the heart, and they want to watch, learn and challenge when they encounter complex and special molds. This is the common characteristic of mold people. On the complexity of the mold structure: the automobile exterior structure is led by the bumper, the automobile interior is led by the instrument, and the automobile structural parts should be led by the automobile air conditioner and the intake manifold. In addition, the molds for chassis, home appliances, and office supplies are also quite distinctive, so today I will use a set of automotive rearview mirror molds to analyze the mold structure in detail.

This Car rearview mirror holder MIM parts, the material is 304 stainless steel, the product is a mirror part, and the number of mold cavities is 2 cavities.

Product Analysis

Car rearview mirror is an important part of car exterior parts, located on both sides of the car, is one of the most important car exterior parts. A car rearview mirror is a device used to allow drivers to observe road conditions during driving, which can be said to be the driver's eyes. Automobile rearview mirror is generally composed of mirror ring, base, mirror shell, bracket, rotating shaft and other parts.

If this product is based on the general product analysis idea, if the main ejection direction is along the direction of the back mold bone position or the column position, the mold structure will inevitably be very complicated, and a large number of undercuts will occur, resulting in many and complex mold structures.

Therefore, choosing the main shaft hole position as shown in the following figure as the main ejection direction will make the mold structure simpler than the above. The side adopts the oblique row position core-pulling structure, and the thimble, the cylinder, etc. need to be designed in the row position.

Product forming process

The basic process steps of metal injection molding are: first, select metal powders and binders that meet the requirements of MIM, and then use appropriate methods to mix the powders and binders into a uniform feed at a certain temperature. After injection molding, the obtained formed blank is sintered and densified to become the final product after degreasing treatment.

1. MIM powder and milling technology

MIM has higher requirements for raw powder, and the selection of powder should be conducive to mixing, injection molding, degreasing and sintering, which are often contradictory. The research on MIM raw powder includes: powder shape, particle size and particle size composition, specific surface area etc., Table 1 lists the properties of the raw material powders most suitable for MIM.

Due to the very fine requirements of MIM raw material powder, the price of MIM raw material powder is generally high, and some even reach 10 times the price of traditional PM powder, which is a key factor limiting the wide application of MIM technology. method, ultra-high pressure water atomization method, high pressure gas atomization method, etc.

2. Binder

Binder is the core of MIM technology. In MIM, the binder has the two most basic functions of enhancing flowability for injection molding and maintaining the shape of the compact. In addition, it should be easy to remove, non-polluting and non-toxic. Due to the characteristics of low cost, reasonable cost, etc., a variety of binders have appeared. In recent years, the selection of binders is gradually changing from the selection based on experience to the design of binders in a targeted manner according to the requirements for degreasing methods and binder functions. direction of the system.

The binder is generally composed of low molecular components and high molecular components plus some necessary additives. Low-molecular components have low viscosity, good fluidity and easy removal; high-molecular components have high viscosity and high strength, maintaining the strength of the formed blank. The proper ratio of the two can achieve high powder loading, resulting in a product with high precision and high uniformity.

3. Kneading

Mixing is the process of mixing metal powder with a binder to obtain a uniform feed. Since the nature of the feed material determines the properties of the final injection-molded product, this process step is very important. This involves various factors such as the way and sequence of addition of binder and powder, mixing temperature, and characteristics of mixing equipment. This process step has always been at the level of relying on experience and exploration. An important indicator for the final evaluation of the quality of the mixing process is the uniformity and consistency of the obtained feed.

The mixing of the MIM feed is accomplished under a combination of thermal effects and shear forces. The mixing temperature should not be too high, otherwise the binder may be decomposed or the two-phase separation of powder and binder will occur due to too low viscosity. The commonly used mixing devices for MIM are twin screw extruder, Z-shaped impeller mixer, single screw extruder, plunger extruder, double planetary mixer, double cam mixer, etc. These mixing devices All are suitable for preparing mixtures with viscosity in the range of 1-1000Pa·s.

The mixing method is generally to first add high melting point components to melt, then cool down, add low melting point components, and then add metal powder in batches. This can prevent the gasification or decomposition of the low-melting-point components, and adding metal powder in batches can prevent the rapid increase of torque caused by too fast cooling, and reduce equipment losses.

For the feeding method when powders of different particle sizes are matched, the Japanese patent introduces: first add coarse 15-40um water atomized powder into the binder, then add 5-15um powder, and finally add powder ≤5um, so that the obtained There is very little variation in shrinkage of the final product. In order to evenly coat a layer of binder around the powder, the metal powder can also be directly added to the high melting point component, and then the low melting point component is added, and finally the air can be removed. For example, Anwar will directly add the PMMA suspension to the stainless steel powder and mix, then add the PEG aqueous solution, dry it, and then remove the air while stirring. O'connor uses solvent mixing, first dry mix SA and powder, then add tetrahydrofuran solvent, then add polymer, after tetrahydrofuran escapes in the heat, add powder and mix, can get uniform feeding.

4. Injection molding

The purpose of injection molding is to obtain a defect-free, uniformly arranged MIM shaped body of the desired shape. First, the granular feed is heated to a certain high temperature to make it fluid, and then injected into the mold cavity to cool down to obtain a rigid body of the desired shape, and then taken out from the mold to obtain the MIM formed blank. This process is consistent with the traditional plastic injection molding process, but due to the high powder content of the MIM feed, the injection molding process has great differences in process parameters and other aspects, and improper control is prone to various defects.

5. Degreasing

Since the emergence of MIM technology, with the different binder systems, a variety of MIM process paths have been formed, and the degreasing methods have also been varied. Degreasing time was reduced from the initial days to a few hours. From the degreasing step, all degreasing methods can be roughly divided into two categories: one is the two-step degreasing method. The two-step degreasing method includes solvent degreasing + thermal degreasing, siphon degreasing - thermal degreasing, etc. The one-step degreasing method is mainly a one-step thermal degreasing method, and the most advanced method is the amaetamold method. Several representative MIM degreasing methods are introduced below.

6. Sintering

Sintering is the last step in the MIM process, and sintering eliminates the pores between the powder particles. Make MIM products reach full densification or close to full densification. Due to the use of a large amount of binder in the metal injection molding technology, the shrinkage during sintering is very large, and the linear shrinkage rate generally reaches 13%-25%, so there is a problem of deformation control and dimensional accuracy control. Especially since most MIM products are special-shaped parts with complex shapes, this problem becomes more and more prominent, and uniform feeding is a key factor for the dimensional accuracy and deformation control of the final sintered product. High powder tap density can reduce sintering shrinkage, and is also beneficial to the sintering process and dimensional accuracy control. For products such as iron-based and stainless steel, there is also a carbon potential control problem in sintering. Due to the high price of fine powder, the study of enhanced sintering technology of coarse powder compact is an important way to reduce the production cost of powder injection molding, which is an important research aspect of metal powder injection molding research.

Due to the complex shape and large sintering shrinkage of MIM products, most products still need post-sintering treatment after sintering, including shaping, heat treatment (carburizing, nitriding, carbon-nitriding, etc.), surface treatment (finishing, ion nitrogen, etc.) chemical, electroplating, shot peening, etc.)

7. Mold structure

The inner and outer sides of the product are inverted, and the cylinder is core-pulled, and the outer side structure also adopts the cylinder core-pulling.

Our Service

Pre-sale

Evaluate according to drawings or products, calculate the price, and submit it to the buyer for confirmation

On sale

The production process of all products is supported by the production system and delivered according to the mutually agreed time. (If the size of the drawing needs to be changed in the middle, the buyer is responsible for the inconsistency with the original drawing. If we fail to meet customer requirements during the modification process, a full refund will be given)

After sales

After handing over the product, we will seal all the buyer's molds for safekeeping.

(Problem solving) If there is a second or third revision in the production process, we will reply within 1 hour at the earliest, and we will solve customer problems within 8 hours at the latest depending on the situation of products that need to be evaluated.

Why Choose US?

Our R&D team	Zhongwei Precision Co., Ltd. and Central South University have a R&D team of 10 people. They develop more than 400 products each year, which is more than 68% higher than the same industry, and have obtained more than 20 patent certificates.
Our technical team	Zhongwei Precision has 5 professional engineers in the field of metal injection molding, and 15 technicians responsible for workshop management.
Our philosophy on quality management	1. Focus on the customer Organizations depend on customers, so organizations should understand customers' current and future needs in order to meet customer requirements and exceed their expectations. 2. Leadership Organizers unify the purpose, direction and internal environment of the organization and create an environment in which employees can fully participate in the achievement of organizational goals. 80% of quality problems are related to management and 20% are related to employees. 3. Full participation Employees at all levels are the foundation of the organization's survival and development, and only with their full participation can they bring benefits to the organization. Job responsibilities include all staff (from general manager to grassroots staff). 4. Process Approach Manage related resources and activities as a process to achieve desired results more efficiently. Flowchart method. 5. A systematic approach to management Identifying, understanding, and managing a system of interrelated processes against set objectives contributes to the effectiveness and efficiency of an organization. The principle of the hoarding of the wooden bucket. 6. Continuous Improvement It is an eternal development goal of the organization. PDCA cycle. 7. A fact-based approach to decision-making: Logical analysis or judgment of data and information is the basis for effective decision-making. Speak with data and facts. 8. Mutually beneficial supplier relationships Enhance the ability of the organization and its suppliers to create value through mutually beneficial relationships.
Device resources	The company has 10 MIM production lines, CNC and intelligent automated production workshops for production lines, which can guarantee the production of millions of MIM parts per day.
System Certification	ISO9001, ISO14001, IATF16949 certification
Port	It is 200 kilometers away from Tianjin Port, and goods can arrive at the port within 24 hours.

Process After Sintering

1. Heat treatment: annealing, carbonization, tempering, quenching, normalizing, surface tempering

2. Processing equipment: CNC, WEDM, lathe, milling machine, drilling machine, grinder, etc.;

3. Surface treatment: anodizing, powder spraying, chrome plating, painting, sandblasting, nickel plating, galvanizing, blackening, polishing, bluing, etc.

Moulds and Inspection Fixtures

1. Mold service life: usually semi-permanent. (except for lost foam)

2. Mold delivery time: 10-25 days, (according to product structure and product size).

3. Tooling and mold maintenance: Zhongwei is responsible for precision parts.

Quality Control

1. Quality control: the defective rate is less than 0.1%.

2. Samples and trial run will be 100% inspected during production and before shipment, sample inspection for mass production according to ISDO standards or customer requirements.

3. Testing equipment: flaw detection, spectrum analyzer, golden image analyzer, three-coordinate measuring machine, hardness testing equipment, tensile testing machine.