Oil & Grease Lubrication for Made to Order Bearings

Oil & Grease Lubrication for Made to Order Bearings

          The importance of an oil depends mainly on its film forming ability which depends further on its viscosity.

         An oil of lowest viscosity is generally more suitable for an application since a higher viscosity oil will waste power to overcome the internal friction of the oil itself

          There are many ways to supply a lubricant to a bearing.  We will explore the different options below.

    

Pressure lubrication is probably the most positive and efficient means to provide lubricant to a bearing.
In addition to offering a more copious supply of oil lubricant, up to an average pressure of 50 PSI, it coats the bearing, maintaining a more stable viscosity range and it assists in flushing out dirt and wear debris from the bearing surface.

        

Oil bath lubrication is where the bearing is submerged in oil which makes it the next reliable method to the pressure-fed oil. The shaft speed should not be so great as to cause excessive churning of the oil.

Splash-fed lubrication involves the oil being splattered onto the bearing surface by movement of other adjacent parts. The housing should be reasonably oil-tight to prevent excessive loss and leakage of the lubricant.

         

Oil ring lubrication involves a revolving or processing ring on a shaft in contact with the oil sump. When the shaft is at low speed, sufficient oil may not be brought to the bearing surface or if the shaft speed is too great, the oil will be centrifuged beyond where it is needed. It also may not keep pace with the oil required.

For best results, it has been proposed that the peripheral speed should be in the range of 200 to 2000 feet per minute. The safe load based on full hydrodynamic lubrication mode should be reduced by one half of pressure lubricated bearings.

Wick or waste-pack lubrication delivers oil to a bearing surface by capillary action of a wick or waste-pack as done in many old railroad axles using bobbitted bronze backed partial sleeve bearings. The safe load when compared with pressure-fed full hydrodynamic load should be reduced to 1/4 of the load.

Grease-packed bearings: Grease is generally packed to surround the bearing and although is substantially less effective than oil, it is much more permanent but the bearing will generally operate in boundary conditions.

  Lubricant Selection

           The selection of a lubricant is based on various factors such as the type of operation, whether full hydrodynamic, mixed film or boundary film conditions in addition to the surface speed and bearing load involved.
 

          Various lubricant articles suggest some recommended viscosities for specific services.
 

          As a rule of thumb, the following suggested viscosities should be considered on the basis of surface speed with a qualified load.

                                Speed(fpm)                 Viscosity(sus)                   SAE Oil
                                 30 or less                       1200-1800                           80
                                 70                                    800-1200                           70
                                 150                                  500-800                             60
                                 300                                  300-500                             50
                                 600                                  150-300                             40
                                 1200                                120-150                             30
                                 2400                                  90-120                             20
                                 5000                                  40-90                               10
                                 over 5000                            5-40                                 5

          As a general rule of thumb, heavier oils are recommended for high loads and lighter oils for high speeds.
 

          In order to obtain a quick conversion of viscosity (sus) to centistokes (cSt), multiply the (cSt) value by 5. The multiple will be the approximate (sus) value.

         To obtain the (cSt) value, divide the (sus) value by 5.

         These results are reported to be accurate within 7% in the range of75 to 7000 (sus) and 15 to 1500 (cSt).

          But also be cautioned that this assumption should not be used below 75 (sus) or 15 (cSt).

          For more explicit lubrication data, we suggest you refer to the CBBI manual or to the Machine Design article of March 10, 1966.

I hope post wasn't too DRY for you and this helped you learn about lubricating methods with ease. 

Anyway, that's it for now.  Until next time my metal loving friends...

Bearing Design Guide: Chapter Sixteen: Effect of the Casting Method on Bronze Alloys

          The casting method should not be ignored but given consideration of the type of service the bronze alloy will be subjected to.

           In particular, the type of load - whether steady and continuous, intermittent or with shock impact or pounding loads - the surface speeds to be encountered and other important features required to be met.

          The casting method has a definite impact on the bronze alloy such as the resulting grain size, density, hardness, mechanical and physical properties, soundness and structure.

          In general, the slower chilled or cooled casting will give rise to coarser and larger grain size. These have a profound effect on the surface qualities, coefficient of friction, wear rate or wear resistance and loads.

          The faster cooled or chilled castings result in greater density, hardness, finer grain size, improved soundness and structure.

           Referring to the illustrations on the following page, please note the finer grain sizes developed by each method of casting.

          Sand Casting: Since molten bronze is poured into a sand mold, the sand or silica having thermal insulating characteristics, will cause slow cooling or chilling of the casting in air. This slow cooling permits the grain size to grow larger, the density, the soundness and structure to be less than by other casting methods.

          Permanent Molded or Chill Casting: The thermal insulating sand is replaced by nickel steel or cast-iron dies. The metal mold quickly chills the casting and this faster solidification results in finer grain size, no interconnected porosity, finer surface finish and improved physical and mechanical properties.

          Centrifugal Casting: Molten metal is poured into a rotating steel or cast-iron die. The centrifugal force impacts the molten metal against the inside of the die, eliminating any porosity. the rotating or spinning die is then sprayed with water coolant to obtain a faster chill than the first two methods discussed the finer grain size further improves the physical and mechanical properties still further.

         Continuous Casting: The molten metal flows by gravity through a graphite die which is chilled
immediately by the cooling jacket surrounding the die. This faster cooling further reduces the grain size and results in still higher physical and mechanical strength.

          The average increase progressively in the tensile and yield strengths is about 5000 to 10,000 PSI and hardness is increased by 10 to 20 points of Brinell hardness.

          Remarks: To further enhances the physical and mechanical properties of the bronzes, extrusion and forging operations can reduce the grain size additionally. These are special processes and the four methods of casting described earlier in this chapter cannot achieve comparable mechanical and physical strength.

Casting Effect On Grain Size and Density

          So...as you can see above, things may look the same on the outside, but they can be very different on the inside.  It is always important to really understand the final application your part will be used in so you know which casting method would be best for you.

          Well...that's it for today. I say goodbye for now. Until next time my metal loving friends...

How Atlas Bronze Could Help if Santa's Sleigh Broke Down on Christmas Eve

          Every Christmas Eve, countless children lie restlessly in bed, thinking about all the toys that they hope to find under the tree on Christmas morning. They’re barely able to contain themselves as they anxiously await Santa’s arrival, depending of course on how well-behaved they were the past year. 

          

          I love watching my kids look up into the dark, winter sky from their bedroom windows, waiting to catch a glimpse of Santa’s sleigh flying through the air. They point and jump up and down when they see Rudolph’s red nose, and I agreeably nod, even though I know it's simply a blinking airplane light. So few things are as boundless as a child’s imagination! 

          

          One day, a terrible thought crossed my mind. What if  this all really happened and Santa's sleigh did in fact breakdown right before the big day or how devastating would it be if his sleigh broke down during his annual expedition to deliver gifts to the girls and boys of the world? The kids would wake up and rush down the steps only to find the terrifying sight of a Christmas tree without of any gifts beneath it. 

          Well, if Santa’s sleigh did break down, I know just the people who could (probably) fix it. Atlas Bronze of course! 

          If Santa’s sleigh was a real vehicle making these millions of trips all around the world in one night, an obvious source of potential troubleshooting would be with the engine. First, Atlas Bronze would go straight to the source and inspect the engine’s valve seats, or the strength center part of the engine that prevents harmful gases from leaking into the manifold. Aluminum bronze is a key component of the valve seat and also helps prevent corrosion. With the addition of bronze parts for added strength, Santa’s sleigh would be dashing through the snow again in no time!

          Since Santa has been so busy making a list and checking it twice, we’re sure he hasn’t thought about the exterior of his sleigh and how it could endanger him on his merry travels. Before Saint Nick goes on his merry way, he would need to incorporate some architectural bronze into the exterior. Bronze is commonly used in the production of doors, making them nice and strong. As an added bonus, bronze will not generate sparks when struck against a hard surface. So, as Santa lands up on the housetop with a click, click, click, he can ensure that his trusty sleigh won’t slide off of the roof.

          Finally, you can’t forget about the bronze sleigh bells on the reindeer's harnesses. As Santa’s original bells may have rusted over many years, he might go to Atlas Bronze to get the materials he needs for a shiny new outfit for Rudolph.

So, whether its Santa's sleigh or a piece of your machinery we are just a phone call away to save the day!

Revisiting the Ghost of Christmas Bronze

Deck the Halls with Bronze

It’s that time of year again! As the garland is wound up the staircase, the tree is propped up and adorned with ornaments, and strands of light are wrapped around the window frames, you just can’t help but get into the holiday spirit. Even if only half the lights actually light up (resulting in hours of frustration), decorating is one of the most fun parts of the season, especially when done with your loved ones.

The common theme for Christmas decorations involves lots of greens, reds, golds and silvers. We also see a lot of ceramic, cloth and glass in various holiday-themed displays. However, bronze has really made a comeback in recent years as a fresh alternative to those classic colors.

This is because bronze decor can make your home even more glamorous, as the metallic hues add a striking effect to any room.

Although I’m not an interior decorator, I’ve been reading that the professionals are seeing a lot more copper and bronze and jewel tones brought into holiday decor. Furthermore, by integrating bronze into your holiday decor and color scheme, you can create a lavish feel without overwhelming your space.

I found some great examples of bronze decor in my research, and have included them below:

• If you’re looking for a vintage, mid-century, modern feel, you can find antique bronze candle holders. Even better: if you have old candle holders in your attic, you can definitely polish them and make them look brand new! 
• To make your tree shine even brighter than before, add ornaments finished or accented with rich bronze. 
• Angel or star tree toppers with intricate designs and trendy bronze finishes can add the perfect finishing touch to your Christmas tree. 
• If you’re having company over for a nice dinner, you can set your table with bronze charger plates. Charger plates are large, decorative plates used to dress up dinner tables at parties and other special events. 
• Bells, especially church bells, have traditionally been associated with Christmas for a long time. Hanging bronze bells from the tree or in the doorway will create a traditional look for your home. 
• And, as you wrap presents for your family and friends, try a dark bronze, shimmering wrapping paper to add a classy, modern style to your gift-giving. 

Bringing these metallic elements from the tree to the mantel to the front yard or door, you can create a cohesive, simple decorating scheme with a modern edge. And you probably won’t want to take the decorations down!

Tall, Dark and Wise

This is a blog post from my colleague Ruth Smith a few years back.  It is a wonderful read and I wanted to share it again!

There it stands against the wall.  Tall, dark and wise.  Within it’s frame lies over 50 years of Bronze, Copper, Iron, Foundry, Specification and general Mill knowledge that could rival any well stocked institution.  At times it receives visitor after visitor stopping only to drink from it’s wealth of knowledge but never to clean it!.  What could I be referring to?  Well, that would be our wonderful Resource Library.  Our owner, Tom Smith, has been collecting it’s contents for over 30 years and let’s just say -- it’s impressive. 

In this post I am going to highlight one of the most requested Resources that we offer. This would be our ASARCO Resource.  It was assembled by the American Smelting and Refining Company (http://www.asarco.com/) sometime in the 1960’s.   I suspect that it is so popular today because it was the first compilation featuring Bronze/ Brass information that was of specific use to both a designer / engineer as well as a foundry man. It covered two major sections:  (1) Application & Selection of typical copper alloys and (2) Foundry Characteristics of the copper base alloys and a tabulation of foundry casting problems. 

For those of you who do not know the name ASARCO, here is very brief history:

(Excerpts taken from Funding Universe)

Founded in 1899 as American Smelting and Refining Company--known informally as ASARCO--the company was a giant from the start. Founder Henry Rogers--along with William Rockefeller and the copper-rich Lewisohn brothers, Adolph and Leonard--had formed the United Metals Selling Company in the 1890s. This trust was so successful that they launched the even larger American Smelting and Refining Company in 1899. At its creation ASARCO consisted of 23 different smelting companies. Conspicuously absent from the ASARCO roster were concerns controlled by the Guggenheim family. In 1899, Rogers invited the Guggenheims to become part of ASARCO. They turned down his offer. The Guggenheims were not interested in being part of an organization that was not under their family control. Over the next couple of years, the Guggenheims took the matter into their own hands and gained control of ASARCO through aggressive business tactics.  As the years progressed and ASARCO experienced acquisition, expansion, two World Wars,  the Great Depression, Roosevelt’s Silver Purchase Plan, and controversy, ASARCO would today wind up being a world leader in the production of nonferrous metals, including copper, lead, zinc, silver, and gold.

(Again very brief history....you can read all about ASARCO’s history by visiting, http://www.fundinguniverse.com/company-histories/asarco-incorporated-history/)

Now that you are somewhat familiar with the history and industry relevance of ASARCO let’s dig into what the Guide has to offer.  It is broken down into (5) sections, Sections 1-3 were geared towards the Designer/Engineer and Sections  4-5 was geared towards the Foundry man.  Although I think today all of the Sections are applicable to any readers.

Overview of Section 1:  Guide to the Selection of Brass & Bronze Casting Alloys

This section tackles the Bearing Properties, Color, Corrosion Resistance, Conductivity, Machinability, Mechanical Properties, Availability of Castings for Brass & Bronze Alloys.  It explains why Brass and Bronze Casting Alloys are the standard materials for Bearing applications.  It touches upon how these alloys when properly specified and designed are resistant to deformation, excellent wear properties and in some cases able to operate for long periods of time without lubrication.  It also explains why the color of the material you are choosing is important and what general color group to expect from the different alloys.  Some of the other features to take away is that this guide references  alloy names such as Everdur, Tombasil and Herculoy. (Which we still have customers coming to us to quote)

Overview of Section 2: Characteristics & Range of Properties

This section breaks out the main groups of Brass / Bronze Alloys:  Tin & Leaded Tin Bronzes, Red & Semi-Red Brasses, High Leaded Brasses, and more.  This section covers the Typical Properties and Nominal Chemical Compositions of the mentioned groups.  But I like the fact that it references them by their nominal chemical composition, which is nice, because we do still have those customers with older prints who come to us referring to an alloy as 88-10-2.  It also gives some overview of each of the groups, their principle characteristics, commercial applications (which has changed slightly over the years) and any other important facts. 

Overview of Section 3:  Miscellaneous Specifications

This section is my favorite.  It not only lists the Chemical & Physical Comps for all the various Brass & Bronze Classifications BUT it gives the old school Ingot Number, Numerical Designation and Specification Numbers for each of group.  It also breaks down the Special Casting Specifications for ASTM, SAE, Federal Specs, Military and Navy Specifications.  And remember the beauty about this particular guide -- it references the OLD specs which is super helpful if you are dealing with an old drawing calling out for a spec that you have never seen.

Overview of Section 4:  Foundry Practices

This section covers the Melting of the material, Recommended Metal Melting Practices, Pouring the metal, Gating & Risering and Venting.  Again, it breaks out the Foundry Practices into Alloy Group pointing out the highlight within each group.  It even provides a (5) step recommended metal melting practices  and a (4) step recommended Pouring practice.

Overview of Section 5:  Some of the Most Common Brass & Bronze Casting Problems 

This section is pretty self explanatory.  This is a neat section because it breaks it down by Problem and then goes through the process to see where the problem would have occurred. Could the cause of the problem in the Design - Pattern Equipment - Mold Setting or Gating?  This section goes through the thought process. 


I hope you find this resource helpful and if you want your copy for your own digital library please contact me at melissa@atlasbronze.com and I'd be happy to send it on over. 

Happy Reading!

Sand Castles or Sand Castings...

One of the "bronze" stories that comes up every so often here at Atlas is a conversation that one of our sales representatives had with a customer on the phone. So much so, that I thought it would be great to bring it up again. Let me start by saying that on a daily basis our Sales group will talk to engineers, machine shops, architects, farmers, universities, other distributors and the list goes on.  So we are used to helping people who have all different levels of industry knowledge and who come from all walks of life, but this conversation was unique...it really made me think, I wonder how may others may have a thought like this.

Here is how it went... 

One of our Sr. Sales Rep's, received a call from a customer who was looking for some rings in the alloy C95200.  The weight and size requirements immediately told them that we wouldn't be able to get the material "off the shelf" but that the rings would have to Made to Order.  So they proceeded to explain to the customer that the best way for these rings to be made would be as a Sand Casting. And after that, the conversation got a little interesting...


SR:  "So, I think we will need to make these rings as a Sand Casting"

(customer speaking)

SR:  "Sir, I'm not sure I understand what you are asking.....(silence)....um...(silence)...the way we will make these rings is with using Sand Castings"
 
(customer speaking)

SR:  "No sir, the rings aren't made out of Sand....(silence)...they are Bronze castings".  "No sir, we aren't going to ship you Sand Castles, they will be bronze" 

Clearly the man on the phone had no idea what a Sand Casting was and was not familiar with the different Methods of Manufacture available to him.  Weeks later and imagining the look on a customer's face when he opened his box to not find a "Sand Castle", I couldn't help but laugh at myself for having these thoughts and want to share not only this story, but a little knowledge and information on Sand Castings.  

Soooo...here it goes...

Introduction

Sand Castings can be traced back to China as early as 645 B.C.  Casting by means of forming sand was common for small parts but eventually over time and with advances in technology, alternative methods of manufacture would be introduced.  This of course improved quality and efficiency.  But even so the Sand Casting method still remains the most widely used casting process.  Why?  Sand castings are the most economical method to reproduce items in metal. Just add water and the sand can be used thousands of times to cast aluminum or other alloys. Additionally, there are just certain alloys that need to be Sand Casted due of the Shape of the part, Quantities required,  the Specification called out or just the overall cost of the piece(s).  

What is a Sand Casting exactly?

Sand casting utilizes expendable sand molds to form complex metal parts that can be made of nearly any alloy. Because the sand mold must be destroyed in order to remove the part, called the casting, sand casting typically has a low production rate. The sand casting process involves the use of a furnace, metal, pattern, and sand mold. The metal is melted in the furnace and then ladled and poured into the cavity of the sand mold, which is formed by the pattern. The sand mold separates along a parting line and the solidified casting can be removed. The steps in this process are described in greater detail in the next section.

The process is fairly basic, there are six steps in this process:

1. Place a pattern in sand to create a mold.
2. Incorporate the pattern and sand in a gating system.
3. Remove the pattern.
4. Fill the mold cavity with molten metal.
5. Allow the metal to cool.
6. Break away the sand mold and remove the casting.

If your like me you’ll need a visual.....



Please know that I haven’t even scratched the surface when it comes to Sand Castings.  There are 2 main types of Sand Castings;  Green Mold and the Air Set Method.  But from there you have Cold Box, No Bake Molds, Vacuum Molding and the list goes on.  Then of course, you have the different types of sand used.  But I’ll save those topics for another post.  Over the years I have run into neat websites that feature a whole variety of Sand Castings - decorative to practical, small to large, simple to complex.  Here is a website that I like to visit, it keeps the whole process simple, www.foundry101.com.

As always if you have any questions leave me a comment and I'll do my best to help and if not direct you to the best resource for your question!  

Until next time, my metal loving friends...

BIG BLOCK CUTTING VIDEO

BIG BLOCK CUTTING VIDEO

Here at Atlas, its always fun to take a trip into the warehouse to see what the guys are up to. On one particular day, one of our guys was cutting into a C86300 Manganese Bronze BIG BLOCK and we were able capture some video of the process.  For reference purposes the block started off as an 8" thick x 18" wide x 105" long piece of material weighing in at around 5,000 lbs and in the last part of the video the cut pieces are to finish to 1" thick x 8" wide x 16" long.

For years, Atlas Bronze has been cutting Custom Size Plates out of Big Blocks of Bronze (and Iron).  It's always fascinating seeing how our guys in the shop cut this material and after seeing it first hand it was quite impressive to watch. I hope you enjoyed the video and if you have ANY questions at all please feel free to contact us at sales@atlasbronze.com or call 1-800-478-0887.

For your information, Atlas Bronze is currently stocking these Big Block Plates in C86300 Manganese Bronze, C90500 Tin Bronze, C90700 Tin Bronze, C91100 Tin Bronze, C93200 Bearing Bronze, C93700 High Leaded Tin Bronze, C95400 Aluminum Bronze, C95500 Aluminum Bronze & C95900 Aluminum Bronze in a variety of sizes.  We carry most of this material dual certified to ASTM B505 and ASTM B22 both domestic & DFARS.  **If you don't see an alloy or a size (thickness or width) that you need please let us know - chances are we can do it!