91ÊÓƵÍøÕ¾ÎÛ

Published

The Material Difference

In some cases, thick-walled, seamless tubes make more sense than solid barstock for certain stainless cylindrical parts.

Derek Korn
Derek Korn
Editor-in-Chief, Production Machining magazine

Share

Leaders-In background
QualiChem Inc.
VISIT SHOWROOM

QualiChem Inc.

Featured Content
View More
Featured Videos
View More
CNC Engineering, Inc.
VISIT SHOWROOM

CNC Engineering, Inc.

CNC Engineering, Inc. specializes in enhancing CNC machine tools to boost manufacturing productivity. Our key services include: - CNC Retrofits a...READ MORE

Featured Content
View More
Featured Videos
View More
Mikron Corp.
VISIT SHOWROOM

Mikron Corp.

Mikron Machining is the leading partner for high performance machining systems to manufacture complex and precise metal components in high volumes....READ MORE

Featured Content
View More
Featured Videos
View More
HEIDENHAIN CORPORATION
VISIT SHOWROOM

HEIDENHAIN CORPORATION

HEIDENHAIN is a world-leading provider of encoders, machine controls, touch probes, digital readouts and metrology solutions—empowering engineer...READ MORE

Featured Content
View More
T J Davies, Co., Inc.
VISIT SHOWROOM

T J Davies, Co., Inc.

Since 1965 we have been manufacturing precision metal products in the United States. We are a veteran-founded, woman-led business dedicated to mak...READ MORE

Featured Content
View More
SMW Autoblok Corporation
VISIT SHOWROOM

SMW Autoblok Corporation

Featured Content
View More
Featured Videos
View More
ZEISS Industrial Quality Solutions
VISIT SHOWROOM

ZEISS Industrial Quality Solutions

Featured Content
View More
Featured Videos
View More

 

For many turning applications, conventional thinking suggests work should begin with solid barstock. However, Sandvik Materials Technology thinks this might not be the most efficient or cost-effective way to produce a cylindrical part from stainless steel, especially if the completed part has a large bore. Instead, the company says its Hollow Bar line of thick-walled, seamless stainless tubes might make more sense for these applications because it can reduce tooling costs and lower overall part costs while eliminating some machining operations.
 
Sandvik’s Hollow Bar material is available in several of the company’s Sanmac austenitic and duplex stainless steel grades (the latter of which is commonly used for oil and gas components). These grades are said to offer improved machinability compared to others. This is possible through better control of the type and amount of non-metallic inclusions while maintaining the corrosion-resistant properties necessary to resist cracking in chloride-laden environments (common with oil and gas applications). Plus, the company says the material offers batch-to-batch uniformity. The various Hollow Bar sizes range in ODs from 32 to 275 mm and are available with a variety of IDs.
 
Consider the part below, a duplex stainless ball valve seat for an oilfield valve assembly. Added Value for Valves (AVV), an Italian designer and manufacturer of complex valve components, recently used this part in machining tests to evaluate the potential time and cost savings using Sandvik’s Sanmac 2205-grade Hollow Bar versus a similar EN 1.4462-grade solid bar.
 
For the solid bar, op-10 work begins with a drilling operation to create the bore followed by facing, external semi-roughing, internal semi-roughing, external finishing, internal finishing and grooving. However, the drilling and internal semi-roughing operations are not required when using the Hollow Bar material, which, in this case, had a 140-mm OD and 100-mm bore. (See the table to the left for a list of the operations and cutting data used for both material types.) For both batches of material, identical op-20 semi-roughing and finishing operations were performed on the back side of each part.
 
Eliminating the op-10 drilling and internal semi-roughing operations yielded considerable overall time savings. Compared to solid stock, that amounts to a time savings of 4 hours per batch of 20 components for an overall productivity increase of 224 percent versus solid stock. Processing time for one part machined was 18.86 minutes for the solid bar versus 5.82 minutes for the Hollow Bar, and, after considering all material and processing costs, the price to produce each component was $64.93 and $43.26, respectively. Therefore, the total cost savings for a batch of 20 components using Hollow Bar was $432.76.
 
During the tests, AVV also noted other benefits with using the Hollow Bar material. For example, it wasn’t necessary for an operator to remove the tangled chips that commonly plague drilling operations. Also, higher cutting speeds could be used while maintaining tool life, and fewer tools were needed for the job. In addition, although overall insert wear was essentially the same for both types of stock, more pronounced wear was found on the rake face of the insert used for the solid bar (likely due to crater wear). This wear pattern was not present on the insert used for machining the Hollow Bar.

 

Read Next

Setting Up the Building Blocks for a Digital Factory
CNC & Machine Controls

Setting Up the Building Blocks for a Digital Factory

Woodward Inc. spent over a year developing an API to connect machines to its digital factory. Caron Engineering’s MiConnect has cut most of this process while also granting the shop greater access to machine information.

Read More
Shop Tour Video: You've Never Seen a Manufacturing Facility Like This
Workforce Development

Shop Tour Video: You've Never Seen a Manufacturing Facility Like This

In the latest installment of our “View From My Shop” series, explore Marathon Precision’s multi-process approach to manufacturing, where blacksmiths and hand-forged dies meet state-of-the-art CNC machining. Discover how restoring classic muscle cars and building custom art projects creates a dynamic shop culture — and draws top talent to this unique and innovative metalworking facility. 

Read More
Why We Ask Machine Shop Leaders to Speak at TASC – The Automated Shop Conference
Automation

Why We Ask Machine Shop Leaders to Speak at TASC – The Automated Shop Conference

TASC is our industry’s premier peer-to-peer automation stage where America’s shop leaders refine the art of metalworking and CNC machining. For conference speakers, it's also an opportunity to showcase your skills and gain exposure for your business. Here are five why stepping into the spotlight at TASC could be your smartest move toward elevating your shop.

Read More