Purchasing An Oilfield / Oil Country Lathe in a Volatile Energy ...

19 Aug.,2024

 

Purchasing An Oilfield / Oil Country Lathe in a Volatile Energy ...

Orders are on the rise at many machine shops serving oilfield and gas producers, but there's no telling how long the good times will last in the unpredictable energy industry. Shop owners must balance the benefits of expanding against the high cost of acquiring a machine like an oilfield lathe.  Shops that buy used CNC machines may be better equipped to handle the ups and downs of this cyclical market.

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Right now most of the United States is turning up the thermostat and bracing for another frigid winter. On a raw day, the arrival of the monthly heating bill seems to add insult to injury.  Thankfully we have a little relief this year - the gas we put in our vehicles is the cheapest it&#;s been in&#;well, forever. 

The bill at the pump and the heating bill illustrate the volatile nature of pricing and demand in the US Energy market. Shifts in the energy industry have a big impact on machine shops that supply parts to oil and gas producers. When business is good, oil and gas companies place orders for big, expensive components. When business slows, shop owners still have to make payments on the big, expensive oilfield lathes required to turn said components. Big bore oil country lathes are known for outstanding precision and dependability in addition to their size, which makes them suitable for many large diameter turning & threading applications. These capabilities come with a premium price tag, however.

Some shops expand by adding used CNC machines or retrofitting existing machines. And with analysts predicting increased demand for drilling equipment over the next five years, it&#;s a great time to add capacity if your shop serves the oilfield industry. 

Learn more:  10 Must-Ask Questions When Buying Used Machinery

By buying used machinery that was manufactured recently, shop owners get updated features and user-friendly CNC controls at significant savings over new equipment.  It can be challenging to find a recent model large capacity oilfield lathe, also called oil country lathes, however,  machines do occasionally come on the market. MMI Auction has several of these models available currently. The Hwacheon Mega 100 x from  pictured at the top of this article is equipped with Siemens 810D controls and a whopping 118 inches between centers. This behemoth is actually the smaller of two similar models currently available through Machinery Marketing International. A higher grade oilfield lathe model is also available: the Hwacheon Mega 100 x from has 236 inches between centers, in addition to a 32 inch chuck and 10.5 inch bore.

CNC retrofits provide another option for cost-conscious shops.  If a machine functions well but is outdated, a retrofit can upgrade the CNC, axis drives, and axis servomotors. Read more about the benefits and process of retrofitting machines that produce oilfield parts here. Alternately, a shop can purchase an older model machine that&#;s already been retrofitted with modern controls.  This Warner Swasey SC36 Big Bore Lathe (pictured left) was retrofitted in with Fagor controls and all new electrical components. It has a 13 inch bore, 36 inch chuck, and a new 75 HP GE spindle motor. The axis and spindle drives were also replaced in , along with the servomotors, coolant motors and more.

Some shops would rather purchase an older machine and do the retrofit on site. This allows the shop to add specific capabilities, controls, and upgrades to meet the machine shop's needs. This Mori Seiki SL-80B from (below right) is fully functional as it is, but it would also be an appropriate purchase for a shop looking for a workhorse that they can upgrade later. It comes with a Fanuc 15T control, chip conveyor, complete coolant system, splash guard, tool holders, hand tools, and a 32 inch 3-Jaw Chuck.

The machines mentioned in this blog are just a few of the large-capacity lathes and big bore lathes available for sale from Machinery Marketing International as of December . MMI also provides full logistical support to help you move these large machines into your shop.

 

 

Buying a Lathe: Spindles and Tailstocks

After considering what sorts of workpieces your turning machine will need to handle, and taking a good look at tooling options, it&#;s a good time to cover what kinds of spindles lathes might have, and what factors are good to keep in mind when choosing a new machine. 

Belt-Driven or Direct-Drive Spindles

The spindle on a turning center is either belt-driven or direct-drive. Generally, belt-driven spindles represent older technology. They speed up and slow down at a lower rate than direct-drive spindles, which means cycle times can be longer. If you&#;re turning small-diameter parts, the time it takes to ramp the spindle from 0 to 6,000 rpm is significant. In fact, it might take twice as long to reach this speed than with a direct-drive spindle.

A small degree of positional inaccuracy may occur with belt-driven spindles, because the belt between the drive and the positional encoders creates a lag. With integral direct-drive spindles, this is not the case. Ramping up and down with a direct drive-spindle happens at a high rate, and the positional accuracy also is high, a significant benefit when using C-axis travel on live-tooling machines.

A2 Spindle Noses

Lathes are designed to have an American Standard spindle nose on the front of the spindle motor. Tapered spindle noses come in various sizes to hold the chuck or threaded spindle mount. A2 and B2 are both short-taper spindles; the only difference between them is the method in which the chuck is mounted. Type L refers to long-taper spindles, and Type D features a camlock mounting used on many engine-lathe spindles.

The good news is, your machine tool manufacturer has the spindle nose selection worked out based on the size of the chuck, diameter of barstock you intend to machine and the horsepower needed. The spindle nose will be properly sized for the machine.

Spindle Speeds, Horsepower and Torque

Today&#;s CNC lathes are designed for specific ranges of stock diameters. Basically, you buy a machine to cut a specific, maximum workpiece diameter. If you&#;re cutting 2-inch-diameter barstock, the machine will be designed for running small diameters using higher-speed, 6,000-rpm spindles, and with the right amount of horsepower and torque.

For more information, please visit Oil Country Lathe For Sale.

Generally, big lathes have high torque (twisting power) due to the weight of the mass spinning in the chuck. As a rule, the bigger the workpiece and the slower the spindle speed, the more torque required.

If the parts you are running require a machine with a 10-inch, big-bore chuck, the spindle will be designed to deliver slower speeds at more horsepower. This creates the torque to take bigger cuts for more stock removal. As the cutter gets closer to the center of the stock, the machine will automatically speed up to, say, 700 rpm to maintain the proper surface footage. Obviously, it doesn&#;t make sense to use a big-bore lathe to do small-diameter work.

The operation that typically requires peak horsepower is heavy-duty, inner-diameter work, such as using big drills to make holes in the barstock before finish-boring. In this case, Z-axis horsepower might be the limiting factor. For example, a 2-inch drill may require a 20-hp spindle motor to get the force needed to perform this operation.

Programmable Tailstocks

A built-in, numerically controlled tailstock can be a valuable feature for automated processes. A fully programmable tailstock provides more rigidity and thermal stability. However, the tailstock casting adds weight to the machine.

There are two basic types of programmable tailstocks&#;servo-driven and hydraulic. Servo-driven tailstocks are convenient, but the weight they can hold may be limited. Typically, a hydraulic tailstock has a retractable quill with a 6-inch stroke. The quill also can be extended to support a heavy workpiece, and do so with more force than a servo-driven tailstock can apply. This is an advantage if you&#;re machining a piece that weighs, let&#;s say, 2,000 pounds. Using the programmable tailstock to push the part helps support its weight in the chuck.

This is part three of a four-part series about buying turning machines. 

 Find more insights about acquiring a new machining center by visiting the Techspex Knowledge Center, &#;Guide to Buying Machine Tools.&#;

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