Purchasing Guildlines

The ordering of stainless steel castings takes a certain amount of time and energy to qualify a potential supplier foundry. To get the best value from the stainless steel casting also requires a cooperative effort on the part of the customer and the supplier foundry from the early stages of the design through to the end manufacturing process. Good planning ahead of time will pay dividends for both you (the customer) and your supplier foundry.

youzhen supply professional and honest service.

The purpose of requesting a quotation for a stainless steel casting is basically to determine the lowest purchased casting cost. The customer then must weigh all of the provisions of the quotation including exceptions taken to drawings, specifications, and processing requirements, as well as supplier foundry experience, tooling requirements, tolerances, finish allowances, and delivery. Such factors as reduced machine work, better tolerances, improved delivery schedules and reliability are particularly important to determine the lowest end cost of the casting.

To avoid misunderstandings, reduce costs, and expedite the processing of quotations, all or some of the following information should be included in a request for a quotation:

• Design &#; What is the part? See design below.
• Quantity &#; What is the anticipated or required volume, both first order quantity and annual quantity?
• Material and inspection requirements &#; what should the part be made of, and how should the part be tested before delivery?
• Actual or estimated casting weight. Actual weight information is preferred. Estimates can be provided by the supplier foundry in the absence of actual weight information, but this may require offering prices that are subject to changes based on the actual weight of the casting(s) in question at the time of production.
• Drawing &#; Machine drawings are preferred over casting drawings. Drawings or sketches are mandatory if samples are not available. Drawing should include dimensional tolerances, indications of critical areas and surfaces to be machined. See machining below.
• Heat Treatment &#; Whether to use solution treatment after stainless steel casting?
• Surface Finish &#; Any special surface finish requirement?

Design

To achieve the most efficient production and the highest quality product, the part should be designed to take advantage of the flexibility of the stainless steel casting process. The stainless steel foundry must have either the designer&#;s drawings and know the length of the run (number of parts to be made).

Stainless steel castings are generally finished with un-machined as-cast surfaces, unless otherwise specified. To take advantage of the stainless steel casting process, the supplier foundry should also know which surfaces are to be machined and where datum points are located. The acceptable dimensional tolerances must be indicated when a drawing is provided. Tolerances are normally decided by agreement between the supplier foundry and customer. Close cooperation between the customer&#;s design engineers and the supplier foundry is essential to optimize the stainless steel casting design.

Material

There are several stainless steel grades (304, 316, 304L, 316L, 17-4 ph, , etc) available in stainless steel casting process. The purchaser should clearly know the differences of each grade and select the most suitable one to produce stainless steel castings. If you are not familar with the stainless steel material, just ask for the help of supplier foundry to determine the right one. Or, just ask the foundry to see if it is possible to cast in two or more grades for your testing, then decide the material based on the factors of low cost and best working performance.

Once starting the order, do not forget to ask for the material testing report from the foundry, and confirm the material compositions are all within the ranges. Any error on the material compositions may shorten serving life or bad working performance.

Machining

Tolerance refers to the dimensional accuracy achievable for a given production method. For the stainless steel process, mold expansion, solidification shrinkage, and thermal contraction all influence the tolerance of the finished part. Consequently, there are limits for tolerances in an as-cast part. Subsequent machining is commonly employed when a tighter tolerance is required.

In the final analysis the supplier foundry is responsible for giving the designer a cast stainless steel product that is capable of being transformed by machining to meet the specific requirements intended for the function of the part. To accomplish this goal a close relationship must be maintained between the customer&#;s engineering and purchasing staff and the stainless steel casting producer.

Heat Treatment

Heat treatment of stainless steel castings is normally operated before machining. And solution treatment is the only heat treatment method used after stainless steel casting, whose purpose is to improve the inner properties and make machining more easily. Customer should advise if the heat treatment is required when requesting a quotation from the stainless steel foundry.

Surface Finish

In terms of stainless steel castings, there are different surface finish ways, including shot blasting, sand blasting, electropolishing, mirror polishing, etc. Just point out which surface finish way is used for your stainless steel casting project.

Choose the right valve means answering key questions first

Published: August 1,  
Last updated: December 30,  

Knowing what makes a valve the right choice
Valves control gas and liquid flow in almost every process and system. As common as they are, choosing the right valve can sometimes be time consuming and confusing.

Begin valve selection by first gathering some basic information on system performance requirements. Knowing this will make it easier to find the right valve. The five tips in this article focus on how to match valve features with these requirements.
 

Tip 1 &#; Valve size and type
Choose the right valve type. Every valve needs to perform one or more basic functions:

• Shut off flow
• Divert flow
• Mix flow
• Pressure relief
• Backflow prevention
• Adjust flow

Function determines the design of standard valve types. These are some of the most common valve types:

• Check valves
• Ball valves
• Needle valves
• Metering valves
• Toggle valves
• Stopcocks
• Relief valves
• Regulators
• Pinch valves

Properly sizing the valve is also important. The right valve choice means matching the valve&#;s size to expected flow through the system.

Common Valve Types at VMA, Valve Manufacturers Association of America

How to Select the Right Valve (with Pros and Cons) at Indelac Controls

Tip 2 &#; Materials of construction
Know the chemical compatibility requirements. The valve materials need to be compatible with the gases or liquids flowing through it. Plastic valves usually resist harsh or corrosive chemicals better than metal valves.

Contact us to discuss your requirements of valve parts casting manufacturer. Our experienced sales team can help you identify the options that best suit your needs.

Miniature Ball Valves: Plastic, Brass or Stainless Steel? at ISM, Industrial Specialties Mfg.

Chemical Compatibility Chart at ISM, Industrial Specialties Mfg.

Tip 3 &#; Performance requirements
Determine the pressure and temperature requirements. Find out both the temperature and pressure ranges where the valve will be installed. Metal valves tend to withstand higher temperatures and pressures than plastic valves. Metal valves are also usually best for pressurized gases. This is because they tend to be stronger than plastic valves.

A Selection Criterion for Pump and Valve Reliability at Processing Magazine

Tip 4 &#; Check valves have special requirements
Be sure the new check valve will work as expected. Look at the response time needed as well as the cracking pressure required to open the valve.

Another consideration is normally closed vs normally open. There are basic check valve designs that require positive downstream pressure to open. These are usually referred to as normally closed check valves. There are other designs that require a positive backpressure to close. These are usually called normally open check valves. An appropriate choice between these two can improve check valve reliability. It is usually best to base this decision on whether the valve is usually open more or usually closed more during normal system operation.

Some check valve types may not work properly if mounted vertically instead of horizontally. Flow direction (upwards vs downwards) and fluid density both matter for check valve designs that can be mounted vertically.

Checking Out Check Valves &#; An Introduction at ISM, Industrial Specialties Mfg.

Tip 5 &#;Maintenance
Don't forget to consider ongoing maintenance. Any valve choice should include attention to maintenance requirements. This is important for both valve reliability and application stability.

A good example of this are ball valves. They resist clogging, jamming or malfunctioning. But they are not suitable for adjusting flow. Using them to control flow can lead to leaking or premature failure.

Valve connection type affects the ease and speed of repair or replacement. Each connection type (threaded, barbed, push-in, Luer, and so on) has its pros and cons.

Plant and Equipment Maintenance at HSE, Health and Safety Executive

Knowing where to start makes valve choice faster and easier
There it is. Knowing particular information beforehand, makes choosing the right valve easier and more certain. There will always be complications like application requirements, operating conditions and chemical compatibility. Starting with basic valve requirements will simplify and speed up valve selection:

• Valve size and type
• Materials of construction
• Performance requirements
• Check valve specific requirements
• Maintenance planning
   

Some additional resources 

How ISM can help you find the right miniature valve for your application
Personalized customer service and resources available at the ISM website can be a great help when selecting a valve. Available online resources include chemical compatibility reference guides, dimensional drawings and product data sheets. Our online and PDF flow control valve catalogs provide access to a wide variety of miniature valve types, connection types, materials and sizes:

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We offer a line of ideas, so if you don't see it - ask for it. Let us turn your ideas for pneumatic or fluidic circuitry assemblies into reality &#; from conception to finished product.

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