Tumbling Media Composition Matters

Tumbling Media Composition Matters

Mass Finishing

tumbling media composition

Tumbling Media Composition Matters

A Media Composition Resource Guide

The composition of tumbling media plays an important role in your finishing process and determines whether the media is for cutting or finishing. Cutting media will contain abrasives within the composition while, finishing media will either contain no abrasive or very fine abrasive. The main materials used for tumbler media include ceramic, steel, plastic, urethane, or corn cobs.

Ceramic Tumbling Media

Ceramic media is typically made up of a combination of abrasive and clay. The curing time and oven temperatures determine the hardness of the ceramic. A softer ceramic will provide better cutting as the media wears away revealing fresh abrasive under the top layer. There are various cutting speed options available to meet specific finishing requirements.

Applications: Deburring, Deflashing, Burnishing, Polishing, Brightening, Radiusing

Available Shapes: angle cut cylinders, stars, cones, triangles, wedges, pyramids, and specialty shapes upon request.

ceramic tumbling media

Stainless Steel Tumbling Media

Steel media provides shape uniformity, short cycle times, and long-lasting durability. Often used in cosmetic finishing, steel tumbling media does not scratch or damage the parts, but provides a clean surface. Steel media does not cause wear to the machine lining, reducing maintenance costs.

Applications: Stress Relieving, Strengthening, Brightening, Preplate

Available Shapes: pins, ball cones, oval cones, diagonal cylinders, and specialty shapes upon request.

stainless steel tumbling media

Plastic Tumbling Media

Plastic media has a lower density than ceramic and is typically softer. The composition is made of abrasive, bonded with various types of plastic or resins. Plastic is commonly used in applications with softer metals or fragile parts. There are various cutting speed options available to meet specific finishing requirements.

Applications: Deburring, Deflashing, Surface Metal Removal, Fine Finishing, Radiusing

Available Shapes: angle cut cylinders, stars, cones, triangles, wedges, pyramids, and specialty shapes upon request.

Plastic tumbling Media

Urethane Dry Finishing Media

Urethane media eliminates the need for compound in the tumbling process. It has a long-life cycle and reduces many typical use costs. It also eliminates the messy residue often associated with plastic media formulations.

Applications: Deburring, Deflashing, Burnishing, Polishing, Brightening

Available Shapes: angle cut cylinders, stars, cones, triangles, wedges, pyramids, and specialty shapes upon request.

urethane tumbling media

Corn Cob Tumbling Media

Corn cob media is typically used to dry metal parts after tumbling or parts washing cycles. The starch helps absorb water, oil and grit. This reduces the chance for watermarks or stains on the parts. It can also be infused with various buffing and polishing compounds for enhanced finishes.

Applications: Deflashing, Burnishing, Polishing, Brightening

Available Shapes: crushed corn cobs, multiple sizes available

Corn Cob blasting Media

Selecting the Right Media Composition

The desired finishing process or final outcome is a large factor in determining the composition as some media types are more suitable for certain applications than others. When selecting your tumbling media composition, as well as shape/size, the part and desired outcome are major factors. The type of metal is a factor when selecting composition as softer metals need a specific blend for ceramic, as an example.

Process Testing

Testing your tumbling process is vital for selecting the right media. Send us your parts and our processing lab will determine the right media shape and type for your finishing application.

Request Lab Tests

Why Tumbling Media Shape Matters

Why Tumbling Media Shape Matters

Mass Finishing

tumbling media shape

Why Tumbling Media Shape Matters

A Media Shape Resource Guide

Tumbling media comes in many sizes, compositions, and shapes. Each of these factors are a crucial decision within your finishing application. We’re going to breakdown the various shapes of tumbler media in this article. Here is a list of various shapes:

  • Spheres and Balls
  • Triangles
  • Pyramids
  • Pins
  • Arrowheads
  • Wedges
  • Ellipses
  • Nuggets
  • Cylinders
  • Quadrants
  • Cones
  • Ball Cones
  • Ovals
  • Stars
  • Four-pointed stars
  • Diamonds
  • Tetrahedrons
  • Random Shapes

Importance of Tumbler Media Shape

The various shapes of tumbler media all have different advantages for specific tumbling applications. The main items you need to consider when selecting a size are:

  • The ability for the media to cover the full surface area of the part being tumbled.
  • Media will not lodge in any holes or recesses.
  • Speed and smooth flow through the tumbler.
  • Allow for easy separation of media from the parts at the end of the cycle.

There are times when using a combination of media shapes is the best process for an application.

ceramic tumbling media
tumbling media

Triangle Media

Triangular tumbler media is ideal for harder to reach corners and slots on parts. The flat parts of the triangles are effective on straight edges while the edges provide coverage into the smaller areas. Triangular media consists of triangles, arrowheads, and angle-cut triangles, often used in cleaning and deburring applications.

Cone Media

Conical tumbling media is effective for entering holes and passageways on parts without lodging. Typically used in applications that require aggressive action, ball cones are often used for burnishing.

Sphere Media

Spherical tumbling media is ideal for blending and smoothing surfaces. The round shape creates good flow and movement through the tumbler.

Wedge Media

Wedge-cut tumbling media, or often referred to as V-cut cylinders, is a versatile shape that can be effective for many applications.

Cylinder Media

Cylindrical media is ideal for deburring holes and contours. The angled ends are effective at reaching into recesses on parts. Cylinders are also very efficient at removing rust from parts.

Oval Media

Oval tumbling media provides a larger surface-to-surface coverage than spheres, while still providing good flow and motion through the tumbler. Ovals are often used in barrel tumbling applications.

The composition of the media will have an affect on the available media shape options. Stainless steel media can’t be made into all of the same shapes as ceramic and plastic.

stainless steel tumbling media

Process Testing

Testing your tumbling process is vital for selecting the right media. Send us your parts and our processing lab will determine the right media shape and type for your finishing application.

Request Lab Tests

Sand Casting Core Defects Series – Part 2

Sand Casting Core Defects Series – Part 2

Foundry

shell sand core defects
In this two-part foundry series, we explore the most common core defects and provide the most probably casuses. If you run into these core defects, use this troubleshooting guide to check your system. Minimizing the amount of defects in the core making room will boost overall production.

Common Core Defects

Core showing thin walls

  • Melt point too high (above 218 degrees)
  • Lack of heat (below 450 degrees)
  • Invest time too short
  • Sand temperature too cold (below 60 degrees)

Core showing parting line shift

  • Worn locators
  • Missing locators
  • Box made improperly

Poorly drained cores

  • Melt point of sand too low (below 205)
  • Hot spots in core box near blow end
  • Invest time too long
  • Drain time too short
  • Blow hole too small for sand to drain out
  • Sand temperature too hot (above 90 degrees)

 

Core showing thick walls

  • Melt point too low (below 205 degrees)
  • Heat too high (above 550 degrees)
  • Invest too long
  • Sand temperature too hot (above 90 degrees)

Core showing cracks

  • Core walls are too thin
  • Core is under cured
  • Core is over cured in areas
  • Core box is opening uneven
  • Bushings or locators are worn
  • Missing locators
  • Back draft in core box
  • Sand has low hot strength (too weak)

Core sticking in box

  • Sand too cold – should be between 60 to 80 degrees
  • Box too cold – below 450 degrees (450-550 degrees)
  • Box too hot – above 550 degrees (450-550 degrees)
  • Free resin in sand due to vibration or fracturing of sand grains
  • Blow pressure too high – average blow pressure 30-50 lbs (blasting on)
  • Blow hole in blow plate larger than blow hole in core box (blasting on)
  • Blow hole in blow plate off center of blow hole in core box (blasting on)
  • Blow time too long
  • Box has just been cleaned – no film left on surface of core box
  • Box is dirty causing back drafts
  • Lack of wax in sand (release agent)
  • Lack of venting in core box – causing operator to raise air pressure or lengthen blow time (blasting on)
  • Cure cycle is too short – core is yellow – resin sticking
  • Core cycle is too long – core is black – resin is burning on
  • Core box has back draft

Core is showing peel back (voids under skin)

  • Very high melt point of sand (above 220 degrees)
  • Cold areas in core box (more heat-more burners)
  • Burners out in some areas
  • Core box temperature below 450 degrees
  • Vibrator too strong during rock and drain cycle
  • Low density (sand will not stick together)
  • Blow pressure too low (creating low density)
  • Blow pressure too short (causing low density)
  • Too high of blow pressure – and long blow timer (together they cause chilling in the box in vent areas)
  • Cold sand (below 60 degrees)
  • Moisture in blow lines (poor flow ability causing poor density and chilling of the box)
  • Vents plugged (air not getting out)
  • Lack of vents (air not getting out)
  • Lack of seal between core box and blow plate (blowing out which causes low density)
  • Sand may be to coarse
  • Dirty box (excessive build-up from resin and release agent causing poor heat transfer)         
Request a Trial of Foundry Sand Today

Contact our team today and request a trial for our foundry sand products. We offer resin coated sand and silica free sand options.

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120th Anniversary Celebration

120th Anniversary Celebration

Press Release

120 year anniversary

PRESS RELEASE:

Midvale Industries Celebrates 120th Anniversary

Saint Louis, MO: Midvale Industries, a leading supplier of industrial process solutions, celebrates our 120th anniversary this year. Midvale began in 1901 as a local foundry and mining supplier, and today offers an expanded offering to clients across the USA, including process solutions for foundry, die casting, aerospace, automotive, medical, metal finishing, manufacturing, painting and other industrial operations.

Midvale has been inventive and ambitious since the turn of the 20th century, by developing brand new products, strategic partnerships and innovative, engineered processes. Midvale offers unparalleled customer service, paired with cutting-edge automated solutions for foundry, aerospace and finishing operations from coast to coast.

“We are thrilled to celebrate our 120th Anniversary this year,” said Midvale’s President, Gregg Kitzelman. “I believe our success is based on our unique mission, which goes beyond the normal customer and supplier relationship. While we provide our clients with innovative industrial supplies and equipment, our team also acts as customer consultants, working with our clients to continually improve how to use those products and equipment in an economical, safe, and efficient way. I’m so proud of Midvale’s success over the last 120 years, driven by our service model and long-lasting customer relationships.”

Today, Midvale offers the highest quality products and unmatched client service. Backed by a team of trained technical representatives, we strive to be strategic partners to our customers, to increase productivity, improve overall quality, and eliminate health & safety concerns for our customers and partners.

Midvale is proud to have over a century of experience serving our clients, and will continue to push the industry forward through our outstanding customer service, advanced automated technology, top products and services, and highly productive and efficient process applications.

Midvale Industries

 

 

Sand Casting Core Defects Series – Part 1

Sand Casting Core Defects Series – Part 1

Foundry

shell sand core defects

Shell Sand Core Defects Series

Part 1

In this two-part foundry series, we explore the most common shell sand core defects and provide probable causes to help eliminate them. If you run into these core defects, use this troubleshooting guide to check your system. Minimizing the amount of defects in the core room will boost overall production and save money on re-work costs.

When is a shell core at its strongest and weakest?

Strongest:

  • Normally a 3/8″ to 1/2″ thick. For thick wall castings, 3/4″ or greater
  • Complete cure of the entire thickness. Golden brown in color
  • Cold Tensile – 350 minimum. Ideal would be 350 to 500 tensile
  • Good density – Blown tight

Weakest:

  • Wall thickness below 3/8″
  • Wall thickness under cured – yellow in color
  • Cold tensile below 350
  • Loose density – Not blown tight

Common Shell Core Curing Issues:

Core is over cured:

  • Box temperature above 550 degrees
  • Cure timers too long
  • Low melt point of sand (below 205 degrees)
  • Sand temperature too hot (above 90 degrees)

Core is showing uneven cure:

  • Not enough burners (heat) to cover the configuration of the box
  • Burners out (not working)
  • Heat controls or sensors not working (either side of the box)
  • Core in the box too long before removal
  • Loose pieces colder than the rest of the box (move heat closer to loose pieces and mount extra burners)
  • Mixture of low and high melt point sands (improperly blended)

Core is under cured:

  • Box temperature is below 450 degrees
  • Cure timer is too short
  • Melt point of sand is above 218 degrees
  • Sand temperature is too cold (below 60 degrees)

Core surface is very dark but rest of core is under cured:

  • Box temperature too high (above 550 degrees)
  • Cure timers too short

Core Blowability Issues and Defects:

Core Has Poor Blowability:

  • Wet Sand
    • Water in air lines
    • Cold Sand – Below 60 degress. As the sand warms up, moisture is created
  • Low melt point – below 190 degrees. Sand sets up too quick, which slows the movement of the sand during blow cycle
  • Core box too hot – Above 550 degrees. The hotter the box gets, the quicker the sand sets up as it is flowing in, which slows up the movement of the sand
  • Blow valve malfunction – Proper air pressure not getting into sand box

Core Has Loose Blow or Poor Density:

  • Sand low in sand box
  • Vents plugged
  • Low blow pressure
  • Blow timer too short
  • Lack of venting opposite of blow end
  • Lack of vents at dead ends
  • Parting line not tight (sand blowing out)
  • Box too hot (above 550 degrees)
  • Lack of seal between blow plate and sand box
  • Blow valve blowing at wrong box position
  • Lumps in sand box (gets in front of blow holes)

Core Has Swirl Marks:

This core defect is usually found on cores that have a large area between smaller areas. The large area would be 4 inches or greater in diameter. This defect can be caused by:

  • Sand falling into the large area and beginning to set up before the remaining sand fills the area and the two sands do not knit together because of the different times the sand is in contact with the hot box.  Filling the core box faster usually corrects the problem.
  • Air that is trapped in the large area that has not pushed to vents opposite of blow area. As the sand was filling the large area and moving around, the excess air blends in with the sand giving the loose blow, swirl appearance. Usually putting vents in the box where the defect is found corrects the problem.
Are you experiencing defects with your shell cores?

Contact our team today to discuss your defects. Backed by years of expertise, our team can run trials to find the best process within your application.

Contact Us