The quality inspection department of manufacturer should check tungsten contacts and fill quality certificate to ensure that products conform to relevant standards.
According to the provisions of GB / T 2828, checking weld strength, size, appearance and roughness of contact surface of tungsten contacts.

Clients can inspect received tungsten contacts, if the result is not consistent with the mark, they can pose this problem to the manufacturer within three months, if these products still not satisfy the standard made by the two sides after mutual identification, and the products fail.

Every passel of product sample should be inspected in accordance with the following regulations:
The purity, hardness and the quantity of crystals of tungsten: Clients can spot-check a batch of products from the tungsten rods and make a sample at its ¼. Or make the sample for tungsten contacts’ inspection directly; if the results fail, then retest. If one of them is still a failure, then this batch of products fail.
Specific inspection rules can negotiate by clients and manufacturers.


 

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Mark
Identify and mark every pack of tungsten contacts with the following items:
Quality;
Specification;
Batch number;
Production Date;
Type and standard;
With the mark of manufacturers and related inspection department;

Package
Using plastic bags to pack tungsten contacts and then putting them in metal or plastic boxes.
Casing tungsten contacts which having the same type, size and batch number on the same box.

Transport
You need to reinforce the boxes which are used to hold tungsten contacts and in which place the moisture-proof paper.
In transportation, you should keep tungsten contacts from violent corrosion, impact, snow and acid rain.

Storage
The location of tungsten contacts storage must be dry and far from alkali, acid, other corrosive gases and so on.


 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
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Sodium tungstate is a novel agent in the treatment of obesity. In diet-induced obese rats, it is able to reduce body weight gain by increasing energy expenditure. This study evaluated the role of leptin, a key regulator of energy homeostasis, in the tungstate antiobesity effect. Leptin receptor-deficient Zucker fa/fa rats and leptin-deficient ob/ob mice were treated with tungstate. In lean animals, tungstate administration reduced body weight gain and food intake and increased energy expenditure. However, in animals with deficiencies in the leptin system, treatment did not modify these parameters. In ob/ob mice in which leptin deficiency was restored through adipose tissue transplantation, treatment restored the tungstate-induced body weight gain and food intake reduction as well as energy expenditure increase. Furthermore, in animals in which tungstate administration increased energy expenditure, changes in the expression of key genes involved in brown adipose tissue thermogenesis were detected. Finally, the gene expression of the hypothalamic neuropeptides, Npy, Agrp, and Cart, involved in the leptin regulation of energy homeostasis, was also modified by tungstate in a leptin-dependent manner. In summary, the results indicate that the effectiveness of tungstate in reducing body weight gain is completely dependent on a functional leptin system.

 

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1. Metallurgical defects of tungsten blanks can affect the quality of tungsten contacts

Metallurgical defects of tungsten blanks mainly refer to: in the smelting process, tungsten blanks inside form inclusions, porosity and other defects. Moreover, some of these defects, there is no way to exclude even in stamping process, for example, Ni, Fe and other impurities or compounds distribute in the grain boundary. Because the presence of these pores, impurities and other defects undermine the combination of grain surface, so the metal base is not continuous, which will lead to tungsten blanks in the process generate cracks or tears, may also lead to the final product --- tungsten contacts produce splitting and brittle fracture.


 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
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Test methods of tungsten points in interrupter:
Using universal measuring tool to check and measure tungsten points.
According to the provisions in JB / T 9864.2 ------ 1999, weld strength is measurable.
By visual inspection or checking with a magnifying glass, tungsten points’ appearance and weld is known.
According to GB / T 4197 requirements, the number of sections of crystals is counted.
With a surface roughness measuring instrument, the roughness of point surface of tungsten points can be measured.
Purity of tungsten sheet is available according to GB / T 4324.1-4324.30 standards.
Hardness measurements can be in accordance with GB / T 230 rules: If you adopt Vickers hardness measurement test method, the load is 4.904N and should be consistent with GB / T 4340 requirements. Refer to relevant tables, measured values can be conversed and the measurement results should coincide with the provisions of HRA.


 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
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Appearance and size requirements of tungsten points in interrupter:

The appearance requirements of tungsten points:
Smooth appearance. There are no rust, burr, discoloration, cold solder joint and other defects in their surface; Furthermore, its electrodeposition is without peeling, de-plating, leak plating layer and other problems.

Uniform welds. The thickness of the weld ≤¼ the thickness of tungsten sheet.
Point surface of tungsten points do not exist depressions or remaining machining marks, its roughness Ra is less than 0.4μm.

The size requirements of tungsten points:
According to drawings or specifications supplied by customer, or on the basis of the negotiation agreed by customer and supplier.


 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
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Sodium tungstate has been found to correct hyperglycemia in insulin- and noninsulin-dependent models of diabetes when administered in drinking fluid with a low degree of toxicity; thus, it provides a potential treatment for diabetes. In the present report, pharmacokinetic studies with sodium tungstate were carried out in the Sprague-Dawley rat and beagle dog. This drug was administered either i.v. (8.97 mg/kg in rat; 25 and 50 mg/kg in dog) or orally in the form of solution (35.9 and 107.7 mg/kg in rat; 25 and 50 mg/kg in dog). Tungsten was quantified using an inductively coupled plasma method. Pharmacokinetic parameters were estimated using a population approach. Sodium tungstate followed first order kinetics, and plasma concentration-versus-time data were adequately described by a two-compartment model. In rat, bioavailability was high (92%), whereas it was lower in dog (approximately 65%). The total volume of distribution expressed by unit of body weight was much higher when the animal was smaller (0.46 l/kg in rat versus 0.23 l/kg in dog). The total body clearance normalized by weight, 0.19 l/h/kg in rat versus 0.043 l/h/kg in dog, changed as for the volume of distribution. The elimination half-life was two times higher in dog (approximately 4 h) than in rat (approximately 1.7 h). In the range of 35.9 to 107.7 mg/kg after oral administration in rat and 25 to 50 mg/kg after oral and i.v. administration in dog, tungsten plasma concentrations increased in proportion to dose.

 

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Tungsten point properties:
Nice melt resistance;
High purity:≥99.95%;
Hardness: 71 - 74HRA;
Weld strength:≥ 83MPa;
Excellent wear resistance;
Good arc-erosion resistance;

High capability of breaking current;
Size deviation is permitted: dh ± 0.05mm;
The number of crystals is more than 10,000PCS / mm2;
Less transfer consumption due to electro-thermal effect;
Density range is available between 19.1g / cm3 and 19.3 g / cm3;
The carbon content of nail seat base:≤0.10% of the low-carbon steel;
Welding purity of tungsten copper alloy:≥99.95%. (Products are available according to your requirements)



Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
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Tungsten point is an important component which is used for the on-off control of circuit in the switch.
Performance of tungsten products:
Having wear-resistance;
With arc-erosion resistance;
Possessing nice melting resistance;
Owning high capability of breaking current;
Due to electro-thermal effect, its transfer consumption is less.
Tungsten point application:
Tungsten point is widely applied in industry, agriculture, science and technology and defense fields, such as cars, relays, sirens, and Magneto, motorcycles and communications machine.
Technological requirements of tungsten point: With the development of automotive industry, people are stricter with the processing requirements of the tungsten point. They require the rod of tungsten point: own smooth surface, good flatness, nice concentricity and better roundness; crystals in section are fine and uniform and its fibers are short; without cracks.


Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
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