Archive for January, 2015

Lubrication Methods for Roller Bearings

Friday, January 30th, 2015

For rolling bearings to operate properly, they must be effectively lubricated to prevent metal to metal contact of the rolling elements, raceways, and cages. Thus, the primary function of adding lubricant is to separate these surfaces.

The lubricant also will protect the bearing’s surfaces against corrosion. Along with its other functions, a lubricant may also provide sealing against contaminants, or act as a heat transfer medium. It is important to choose a well-suited lubrication for each bearing application.

Operating conditions will determine the correct choice of lubricant, i.e. temperature range, speeds, and surroundings. Note that because the lubricant in a bearing arrangement loses its properties as a result of working, aging, and the build-up of contaminants, it will need to be changed and renewed at regular intervals for proper bearing function. This is called “relubrication”.

Oil is generally used for rolling bearing lubrication when there are rather high speeds, high temperatures, or when heat has to be removed from the bearing position. The most important property of lubricating oil is its viscosity. The lubricant’s viscosity is directly related to the amount of film thickness it can generate, which is the most critical component to achieving separation of the bearing’s rolling and sliding surfaces.

Mineral oils are typically favored for rolling bearing lubrication, with rust and oxidation inhibitors as additives. Synthetic oils can be considered for lubrication in extreme cases such as very low or very high operating temperatures.

Methods of oil lubrication for roller bearings:

Oil bath: Can be used for low to moderate speeds. The oil stays in a pool at the bottom of the bearing, and as the bearing rotates, the oil is distributed and then flows back to the oil bath at the base.

Oil pick-up ring: For bearings operating at higher speeds and temperatures, the pick-up ring circulates oil by hanging loosely to the shaft and rotating with it to transport oil. The oil then flows through the bearing back into the reservoir at the base.

Circulating systems: This method is preferred for high speed operations. With the aid of a pump, oil is circulated to the bearing, drains and returns to the reservoir where it is then filtered and cooled before returning to the bearing.

Oil jet: For very high speed applications, where a jet of oil under high pressure is directed at the side of the bearing. For this, the oil jet’s velocity must be high enough to break through the turbulence surrounding the rotating bearing.

Oil mist: Used today only in unique conditions, oil and air under suitable pressure are supplied to the bearing housing.

Oil spot method: Uses compressed air to transport lubricant directly to the bearing. The oil is sent into the airstream supply lines to the bearing housing at set time intervals.

51 V-Belt Applications

Friday, January 23rd, 2015

By definition, V-belts are: A belt with a flat bottom and tapered sides which transmits motion between two pulleys.

The V-belt has a general cross-section shape that is trapezoidal – hence giving it the name “V”. The “V” shape of the belt tracks in a mating groove in the sheave or pulley. The result is that the belt cannot slip off. V-belts tend to wedge further into the grooves as the load increases, and tend to need larger pulleys because of their thicker cross-section as opposed to previously popular flat belts.

V-belts are the workhorses of industry. Readily available from nearly every distributor and adaptable for a multitude of purposes. V-belts are easily installed and removed, quiet, and low maintenance. They are available in a wide variety of standard sizes and types, and capable of transmitting nearly any amount of load power. In addition, V-belt drives permit large speed ratios and generally endure for the long haul.

If an application requires higher power, V-belts can be joined side-by-side and run on matching multi-groove sheaves. These are then called Multiple-V-Belt drives.

Below is a list of 51 V-belt applications. Take a look – you may not even know what all V-belts are in to these days. The below list represents a wide array of industries, proving just how widely-used and versatile they are.

  1. Agitators
  2. Paddle or Propeller, Vertical or Horizontal Screw
  3. Bottling Machinery
  4. Car Dumper, Car Puller
  5. Brick Press
  6. Compressors
  7. Lobe, Rotary
  8. Cranes and Hoists
  9. Dredges
  10. Cable Reel, Conveyor
  11. Cutter Head Drive, Jig Drive
  12. Pump, Screen, Stacker, Utility Winch
  13. Dynamometer
  14. Elevators
  15. Fans
  16. Food Industry
  17. Slicer, Dough Mixer, Meat Grinder
  18. Generators
  19. Hoist, Railway Services
  20. Laundry Machines
  21. Tumbler, Washer
  22. Extractor Line Shafts
  23. Driving Processing Machine
  24. Lumber Industry
  25. Edger, Log Haul
  26. Sawdust Conveyor
  27. Slab Conveyor, Sorting Table
  28. Planer (reversing), Plate Planer
  29. Metal Forming
  30. Wire Drawing, Flattening Machine
  31. Mills (Rotary Type)
  32. Tumbling Barrel
  33. Concrete – Continuous & Intermittent
  34. Paper Mills
  35. Beater and Pulper
  36. Chipper
  37. Pulp Grinder
  38. Printing Press
  39. Pulverizers
  40. Hog, Roller
  41. Pumps
  42. Oil Well Unit
  43. Rubber/Plastics Calendar, Extruder
  44. Screens, Coal and Sand
  45. Sewage Disposal Equipment
  46. Shredder
  47. Steel Cold or Hot Mill, Coiler
  48. Feed Roll
  49. Textile Batcher, Calendar, Loom
  50. Dyeing Industry Machinery
  51. Woodworking Machines

High Heat V-Belts

Friday, January 16th, 2015

A very common question pertaining to v-belts is the effect of heat on them. How does heat affect v-belts and their lifespan? We’ll answer that today.

Most manufacturers publish that for every 35 degree increase in prolonged temperature endurance above 85 degrees Fahrenheit, a v-belt’s life is essentially cut in half.

Each belt has a specific temperature range that it is not meant to exceed. The temperature range guideline refers to sustained temperatures. Thus, operating a v-belt continually within the range will be sustainable, but once outside this range, you run the risk of damaging the v-belt and potentially the machine itself.

Alongside the operating temperature of the area in which a v-belt is present, heat is generated due to the physical flexing of the v-belt as it enters and exits a sheave. Friction is also produced and raises the heat level as the belt is wedged into the groove.

Some tips for keeping the temperature down include: (Source: Belt Drive Monthly)

  • Using the largest sheave for the allowable space. This will help reduce belt flex or resistance and improve cooling.
  • Properly align sheaves and tension belts to the manufacturer’s recommendation.
  • Check sheaves for wear and replace if wear exceeds 1/32” in the groove.
  • Consider adequate ventilation and air flow in belt guard designs.

There are different types of v-belts you can use for different temperatures. The standard v-belt typically can manage in a range of -18 to 158 degrees Fahrenheit. Raw edge belts, a step up in handling higher heat, can withstand -1 to 212 degrees Fahrenheit. These belts have had notches taken from the underside so as to allow for an increase in air flow. This makes them optimal for high heat applications.

Some v-belt manufacturers are sending out more and more AOH belts as the new standard, which are oil and heat resistant from temperatures -22 to 212 degrees Fahrenheit.

For higher heat applications, there are belts that can even withstand sustained temperatures of up to 302 degrees Fahrenheit, for instance the EPDM poly v-belt.

Note: High heat v-belts are typically more expensive and may require a minimum purchase order amount due to the quality natural rubber products they are made from.

When to Use Synthetic Lubricant

Friday, January 9th, 2015

It isn’t always clear which lubricant to choose, especially since the introduction of synthetics into the market. There are many questions when it comes to when to use a synthetic lubricant. Although it would be difficult to answer for every possible scenario, the following information should prove useful for you when selecting the right lubricant for the job.

Naturally occurring lubricants, or mineral oils, contain organic compounds of oxygen, sulfur and nitrogen. These compounds are problematic, because they enable oxidation and acid development. Then there is the issue of the formation of sludge, particularly in high-temperature applications.

The varying molecules in mineral oils also have differing shapes, which results – at the molecular level – in irregular lubricant surfaces. Irregularities generate friction within the fluid itself, increasing power requirements and reducing efficiency.

In contrast, the components of synthetic lubricants are high in purity with strong molecular bonds. The end product is a pure compound, less vulnerable to oxidation, more resistant to breakdown, and of a uniform molecular size. Therefore, their protective characteristics are more predictable.

There is a broad selection of synthetic lubricants, ranging in viscosities and consistencies, and even “green” environmentally friendly varieties. And they are generally affordable compared with conventional petroleum-based lubricants.

Synthetic grease costs haven’t risen as rapidly as conventional greases, thus reducing the cost differential between the two categories. This is largely due to stricter environmental and worker safety requirements in the industry.

The difference between conventional and synthetic greases can be found in the lubricating agent. Petroleum-based greases involve mineral oil, for example, whereas synthetics employ silicone or other engineered chemical compounds.

Synthetic lubricants have long been considered the right choice for applications involving extreme temperatures, loads and speeds.

The upper temperature limit for conventional greases is approximately 285 degrees F. In this range, synthetic greases exhibit better mechanical stability. Conversely, synthetic greases also excel at lower temperatures, where conventional greases may become stiff and lose effectiveness which can prevent bearings from properly rotating.

It appears that synthetics are superior for usage in the extreme zone where temperatures, high loads or flammability are concerning variables.

There is still much debate over whether or not it is in the best interest to use synthetic lubricants over conventional ones 100% of the time. It is best to research for the specific application you are needing the lubricant for, before deciding for yourself.

Timken Fafnir HVAC Housed Units

Friday, January 2nd, 2015

It is vital to have sound bearings for HVAC uses. Noise and premature breakage or failure will result if a unit is lacking sound equipment.

In an HVAC fan motor if bearings become loose the result will be a heavy drag or wear and tear and eventual stopping of the motor. It is very important that the bearings and equipment all run smoothly together, or the motor will be toast. Likely, there isn’t use replacing the motor, so you will want to prevent any heavy wear and tear to extend the life of your system for as long as possible.

If you were to take apart the HVAC fan motor, you would see a heavily rubbed down area on the rotor. So today, I’m going to shine the spotlight on the Timken brand of ball bearing housed units made specifically for HVAC. Their product is quality-made and easy to install. And, most importantly, will allow your system to operate efficiently and effectively.

Timken Fafnir housed units for HVAC are made to reduce vibration, run cooler at higher speeds, extend grease life, and maximize overall performance. A housed unit combines the bearing, housing, seal and locking system into one device for easy installation and operation. Like a traditional setscrew, it locks to the shaft. Within the sturdy housing, each bearing supports radial, thrust, or combination loads.

They are able to achieve these results successfully, due to their patented shaft guard technology and innovative housed design. No nicks, raised metal or permanent shaft damage should occur, prolonging the life of the shaft. This is critical, since shaft replacement can be expensive. Timken’s shaft guarding technology exceeds gripping application requirements, keeps dimensional integrity, and reduces fretting corrosion.

Unlike traditional setscrews, Timken’s shaft guarding technology transfers the pressure of the setscrews through a stainless steel, hardened band which will not corrode to the shaft. This absorbs any problems arising from relative motion typically found in setscrew products.

Of course, Timken also offers a range of application-specific lubricants for operation in industrial environments. Their high-temp, anti-wear, and water-resistant additives will protect in the harshest conditions, reducing downtime and boosting productivity.

It can be a costly game, repairing HVAC issues and damages. That’s why quality equipment truly will go a long way for you.