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Understanding and Getting the Most From Metalworking Lubricants
Understanding and Getting the Most From Metalworking Lubricants By: Jim Szumera - MACOR Published on: 09/2/2012
How can I increase my tooling life and increase my production capacity and yield by as much as 50% or more? The answer is not easy to find. It usually involves many variables and experimentation. One answer may be the metal stamping lubricant. The use of lubricants began years ago without the benefit of science and technology. The criteria for choosing a lubricant was cost and availability. We used everything from kerosene to cooking lard and oil. We applied it with drip cans, brushes, felt pads and hoses without any control, science or technology. Kerosene was widely used in stamping aluminum. Lard oil was thought to aid in deep draw applications. Today, in the age of specialization, I like to think of lubricants as tool of the trade.

Lubricants have a specific job to do. They are formulated to reduce friction, remove heat and afford surface protection. In choosing lubricants today, the main factor is the environment. The other important factors are compatibility with the base metals, the degree of stamping or forming severity, cleaning and maintenance. Lubricants are available as fluids, pastes and films. Fluids are the most common. These solutions can be water base, oil base or synthetic. They can also be supplied as emulsions, where one liquid is suspended in another, usually water. Pastes are used for high pressure applications such as deep drawing. Pastes can also be oil or water base as well as synthetic. For severe metalworking applications, extreme pressure additives, such as chlorine or sulphur compounds are added.

Lubricants must also be formulated for compatibility with the base metal being stamped or formed. The base metals are classified into three categories. The first category is normal surfaces such as cold rolled steel and low carbon steel. The second is the active surfaces such as copper based alloys. The third is your inactive surfaces. This includes stainless steel and other nickel based alloys. Lubricants are usually formulated to meet these criteria. It is important to note that most lubricants cannot be used on all surfaces with any measurable degree of success. In certain applications the lubricants should also be compatible with the tooling itself. Carbide, for instance, has been known to leach or break apart when in constant contact with the chlorine additive in certain lubricants. The chlorine attacks the carbide binder material which causes the failure.

Lubricants today are specifically engineered for certain applications. These new age lubricants are also more costly. The application methods become critical to the overall cost and performance. Years ago lubricants were applied randomly and generously. No real attention was given to the application methods until now. I like to apply the lubricants in the right place, at the right time and in the right amount. This may involve utilizing airless sprayers, felt rollers or flooding the tool, depending upon the requirement. To further control lubricant costs, we must also ensure against contamination. Contamination can come from a number of sources, including the press oils. Any good lubricant can be rendered useless if contaminated. We must also prevent the lubricants from attack by bacteria and algae. This is a simple process of controlling the PH and chemical balance, similar to caring for a swimming pool.

The chemical and lubricant suppliers have a wealth of knowledge and are experts who are willing to work with customers to find answers to stamping problems. This can be a vital part of process improvement.

Do you really need a lubricant in your stamping operation?
There are many applications where a lubricant may not be necessary and only contributes to the cost of the part. The excessive costs may be the lubricant itself, cleaning the part and disposal. When I look at a stamping operation I look at several factors to help me select candidates for running dry. I examine the base metal, stamping speed, temperature and the operation itself. Once I determine a good candidate, I look at the tool design parameters. To eliminate lubricants, several inexpensive changes must be made to the tool itself. I not only modify the tools but I also look at material choices, coatings and tool dynamics. The tools can vary widely in design and construction. Each one needs to be evaluated on an individual basis. Fore more information please contact Macor.

Summary
1. The most important key factor is applying the lubricant in the right place, in the right amount and at the right time.
2. The lubricant must meet or exceed environmental standards as non hazardous.
3. The lubricant must be compatible with the base metal being fabricated. Avoid using the same lubricant for different alloys.
4. The lubricant should be formulated to match the severity of the operation being performed. This may include the use of extreme pressure additives, wetting agents, biocides or rust preventatives.
5. The lubricant should be free from contamination, dirt and grease and should also be protected against algae and bacteria.
6. Utilize mechanical or pneumatic devices to apply lubricant whenever possible. These devices should be properly timed with the stroke of the press or machine cycle. This will go a long way in controlling the costs of the lubricants and also help in the overall performance.
Look for our next discussion on Running Tools Dry.
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Running Older Presses
Running Older Presses By: Jim Szumera - MACOR Published on: 06/19/2012
Tips and Tricks to Producing Quality Parts in Older Machines
Oftentimes I fall into the blame game. Is it the press? Is it the die? I have had new dies installed into presses only to make several hundred hits before the punches would shear. I have had draw dies set up resulting in cracked cups, wrinkling on one side only, galled and sheared. The initial tendency is to address the problem as a tooling issue; after all, it was the tool that failed. If the tool is machined and set up correctly, it can never be a tooling issue. The root cause often lies elsewhere. If a tool fails shortly after set up, one needs to look closely at the press variables. These can be alignment, wear, parallelism, speed, stroke, timing or lubrication. One of the most critical performance criteria is press alignment. Older presses, through neglect, age, off center loads, constant area loads and the floor foundation itself all contribute to miss alignment. Several simple checks should be made to determine the press accuracy and alignment. First, the surface of the bolster and ram need to be checked for flatness. After years of pounding, the ram and the bolster may have an area of impression. A good rule of thumb is .001 per linear foot. Any more than that is trouble. The bolster may have to be reground if it shows excessive depressions. The ram also may have areas of depression. Resurfacing the ram may be too costly and time consuming. To compensate for the ram I may elect to “soft mount” the upper shoe using a hard urethane sheet between the ram and the upper shoe. This acts as a “filler” and will compress slightly on the down stroke. Another method is to mount a pre hardened 4140 plate to the ram, provided you still have adequate shut height. Basically we are installing a new surface to the ram. All high volume heavier material stamping dies should be designed using a 4140 steel die shoe to begin with. The higher strength material will prolong the surface life of the ram and bolster. Using 4140 for the die shoe, in many cases, will allow the elimination of back up plates. That savings will more than offset the increased cost of the shoe. The lower shoe must be supported all the way through the bolster, wherever there are large cutout areas. I have actually encountered a lower die shoe so flexed that the shims behind the bushings slipped under the die block. In another case, slugs actually slipped under the bushings. The die shoes also need to be checked for excessive bending and corrected as necessary. If you are stamping thin materials, you may not experience these types of issues. Short of rebuilding the press, I will modify the tool to improve alignment and prevent shearing, galling or breakage. If I am dealing with older presses I may design my tooling with guided strippers and no press fits. On draw dies, I will allow the draw punches to float and find their own center. This will always make for a better looking even draw. In some applications, involving high speed dies, I will not bolt down the lower shoe. It is allowed to float. Any modifications to mounting methods should be done in a safe and protected manner.

We have listed several ways to help correct the press inaccuracies such as installing pre-heat treated plates to the upper ram, regrinding the bolster, supporting the lower shoe, and various tooling corrections. Other issues that can cause die failures are crank and pitman timing on double crank machines, galling of the press slides and gibs, short guide pins that exit the bushings on the upstroke. This usually results in deflection and “bounce” on the down stroke. The crank assemblies can be out of timing with respect to each other. Another critical component are the isolation units under the press feet. Are they worn or collapsed? The floor foundation is another factor. Does the entire press flex on the down stroke, given the weakness of the floor foundation. I have had instances where the floor was cracked between the press legs and actually flexed. In the idle state, the press checked out fine. Another issue that rears its head slowly is with open back incline presses or OBI type. These presses can "yawn" or open more in the front over time. It may be necessary to actually shim the front of the bolster to compensate. In any case, if you have evidence of press degradation you must set up a plan to address these issues. The plan may include increasing inventory, outsourcing, or running in optional available machines giving time to rework the press, and planning for new presses in the future. You cannot keep running presses in poor condition and expect quality parts every time. Post your ideas.
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Comments

PietroJun 20, 2012 - 9:42 am
I think you'd better change your old presses. I can offer a good bargain. Rgds
CharlieJun 20, 2012 - 1:06 pm
What are you selling?
Jim SzumeraJun 20, 2012 - 1:06 pm
Charles
Thank you for your comment and question. We are marketing our new web site www.stampingworld.com.
The goal of stampingworld.com is to meet the needs of the Metal Stamping populous by providing information to better design, build and produce formed metal parts. To accomplish this, our task is to constantly update and provide new ideas, technical data sheets and free downloads, timesavers, pictorials, solutions and editorial content, free classifieds with great job offerings from great companies to the Metal Stamping Industry. For the advertiser, this creates a unique opportunity to connect with their targeted audience and key prospects, specifically decision makers such as process engineers, tool designers, operations and project managers, and product engineers whose career revolves around the design and manufacture of a metal stamped part. If you have had a valuable experience regarding metal stamping dies and would like to share it, you are welcome to post it on our site in Die Shop Manager, or if you have an opinion you would like to share post it in VIEWPOINT. It’s all free.
FabrizioJun 28, 2012 - 9:05 am
Hello everyone ! We sell and install presses
all around the world. We can offer a complete new line, built by us
or a line that is completely overhauled.
DerylJul 5, 2012 - 9:47 am
Hey Jim,

I wont try to sell you a press, I will just add to the discussion as I assume this was your actual goal.

I was interested in the hard urethane sheet comment, I had heard you could use cardboard for this, but never tried it. I have rarely worked at a shop with older presses that didn't have issues with alignment. I can't stress enough how important it is to have a routine preventive maintenance check on press alignment. Gib clearences are usually a culprit as well, but I am amazed at how many press beds I have seen in my day that have issues as simple as large burrs on them that precision dies sit on, causeing all kinds of trouble-shooting grief. Anyway, I really liked the article.
Jim SzumeraJul 5, 2012 - 1:42 pm
Deryl
I heard the same about cardboard, but have not tried it. My concern would longevity.
CharlieJul 22, 2012 - 1:51 pm
"When running quality parts in old presses it is essential that die alignment be maintained though the entire part of the timing when top and bottom dies are in contact with the material or are overlapping. To that end the die guide posts and guiding elements must be sufficient to keep the correct the alignment in spite of press wear or misalignment. If the die posts cannot be or were not made sufficient to keep the correct alignment then the actual press must be repaired, rebuilt, or replaced or it is not possible to make parts right the first time, every time, and all the time which these days means you cannot stay in business."
TwotenthsFeb 25, 2013 - 2:02 am
The biggest problem that I have encountered is when measuring the ram to bolster. Most people will just measure in a static state but for a true picture you must load all four corners with tonnage jacks which create pressure on all four corners at once. Only then will you discover if they are parallel under load or not. It must put upward force on the press knuckles for a true picture. Measure without load and with load and it will tell you if you need to replace the knuckles or refit them. It is a common problem when you find your guide pins are overheating. I have also created complete 3D Cad drawings of all the presses. I have input all the adjustment variables and have created a new die design standard from it by finding common shut heights between presses and designing all new tooling to fit within those parameters. It allows for much greater flexibility and you can safely take a press down for service. You can then redistribute your press resources to accommodate the dies that were running in it to other presses. This eliminates the outsourcing of tools to other companies who will charge more per part than what we get paid for it. It also allows for more time for needed maintenance as well. You don't need to worry about where to outsource to and for a few days or a week you can do an overhaul on the affected press without outsourcing. Another item is that when any changes are made to press specifications it must be followed up in the 3d model so that you can make sure that the upgrade doesn't interfere with the resource allocation flexibility. At one point we were running all presses 24/7 because we would fall behind due to lack of press maintenance and losing that up time would cause a backlog in production. By implementing the new standards we can now run 24/5 with the weekends open for maintenance. I created 2 standards. One for the large presses with a 54" shut height and one for the standard prog dies with a 24" shut height. If we build all new tooling to those exact standards we no longer even have to adjust shut heights between tools. We have roll in bolsters that are preloaded with the next job and then you just roll them in, punch the die number in to the program, connect the tool protection adjust the part catching belts and start running. Of course you need a coil change but the new coil is already beside the press with the checking fixtures as well. Changeover is down to 10 minutes from last stroke to first stroke on the next tool. Feed in the strip and fully load the die and run a few in full auto then check them on the fixture. Make some very minor adjustments and your running again. It took me over a year to do it all and create the common standards to design to, and it paid off in no time at all. On some presses we built risers for the bolster to make them compatible with the others. We even built a riser to allow 24" dies to run in the 54" presses. It is also designed with the intention of putting it in any 54" press. It did require some capitol expenditure to accomplish but the savings were enormous after full implementation.
Tim DismoreFeb 14, 2014 - 11:47 am
I keep hearing people say use bigger guide posts to correct press problems. This is actually the wrong approach. Die set pins and bushings have only two functions, first is for the toolmaker to align the die sections and punches and the second is storage. Die pins and bushings were never designed to correct a worn press. If you have a press problem you need to address it but trying to correct it with the die will never yield a long term fix.
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Servo Press Technology: Breaking Down the Choices
Servo Press Technology: Breaking Down the Choices By: Randy Kish - Seyi America Published on: 05/24/2012
The flexibility and efficiency of servo presses are challenging tooling engineers and part designers to rethink the way they form. For any company hunting to gain a competitive advantage, having a servo press will be a mainstay. When it comes to a servo press investment, there are varying differences between manufacturers to consider that will impact performance, reliability and cost. While you dream of new and creative ways to form, be sure to rethink power, construction and control.

Rethinking Power

All servo presses replace the main motor, flywheel, clutch and break with a servo motor. The differences are the types of motors and drive trains. The first option is a “hybrid” drive configuration. With a hybrid, a knuckle or link-type drive train is used with a standard high rmp/torque AC servo motor. This hybrid drive configuration allows for a compact and efficient motor, but has drawbacks. For one, the need to “down-gear” a high-rpm motor to generate torque requires more parts, belts and mechanical components, increasing maintenance and service. Because of the knuckle or link-style, you still rely on mechanical linkages to generate thrust which can negatively affect tonnage and torque, especially high in the stroke.
The second option is a “direct drive” servo motor. This motor has a dramatic hi torque/low rpm ratio. In some cases the max rpm is only 340, with a torque rating of 14000 N-m. At such a ratio, less than 40% of the torque is required to accelerate the drive train, leaving 60% or more to accelerate or decelerate the slide or develop press force. This configuration eliminates energy-consuming linkages, down-gearing and other mechanical obstacles. The pinion shaft is connected directly from the motor, and in some instances, directly to the motor (part of the motor, actual rotor.) Only the pinion gear and main gear are needed. This configuration provides better transmission, less maintenance and more consistent energy thru the stroke. Some manufacturers have large capacitors to capture any unused energy, like when the press is not under load, and use it when the time is right.

Rethinking Press Construction
A servo press’s programmable slide speed, position and dwell will open your mind to creative metal drawing and in-die processes. But this versatility introduces new strains, twists and forces on the press frame. Most servo press manufacturers offer conventional gap frame, straight side, or tie-rod constructions. However, other manufacturers argue that conventional structures are not rigid enough to hold tight tolerances under longer dwells and draws without stretching, and elongating the frame. These manufacturers employ a completely different design. Some call it monoblock, others call it honeycomb. In essence, both design the press with low-impact speed in mind and are intended to “box-in” horizontal and parallel support on the slide and bolster, which are located in the center of the frame. Thus, all support is targeted to where it’s needed most, reducing the risk of press damage, as well as floor space.
Speaking of press damage, you cannot overlook the importance of an overload protection system. Most manufacturers offer an upgraded version of the traditional hydraulic overload, understanding that new forces are being entered into the forming process which could alter the way a hydraulic overload works. Other manufacturers have done away with the hydraulic overload and replaced it with an electronic, programmable overload , which may perform better over longer dwells operating closer to rated tonnage.

Rethinking Control

Every manufacturer gives you a means to select and adjust pre-programmed stroke profiles or create freestyle profiles. Beyond that, a servo press controller should offer more than what you’re used to. You should have more standard ways to integrate and orchestrate peripherals, a robust back end for collecting and analyzing data, and a user-friendly front end to put that data to use. The controller is the key to making your servo investment pay off. If you’re not using the most up-to-date and scalable control technology, you’ll soon be upgrading and paying more.
As you weigh the options in servo press technology, you have more choices than ever. With these choices come more information and a better understanding of what to expect, which should help you make the right decision
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