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For gap frame presses, it’s common to use light curtains for point-of-operation safeguarding on the front of the press while using physical barriers for the side, although mirrors may be used to provide three-sided guarding. The light curtain should be configured so that it’s unreasonable to reach over, under, or around the sensing field without detection. The light curtain also needs to be located at a safe distance as required by OSHA and ANSI standards.
Typically, it’s unrealistic for operators/helpers to reach the point of operation from the back of the gap frame. When necessary, it’s most practical to use a physical barrier to prevent access from the rear of the press. Most gap frame presses have fast enough stop times so “walk through” hazards are not a problem; accordingly, horizontal light curtains are seldom a consideration.
On straight side presses, its common to use light curtains as point-of-operation safeguarding devices on the front (operator side of the press). Sometimes it’s practical to also use light curtains on the back side of the press, especially when alternative guarding methods might unnecessarily restrict access to the tooling. In either case the light curtain should be of sufficient height that employees can’t reach over, under, or around the sensing field. Presses with slower stop times may require a safe distance that creates a “walk through” hazard (allowing an operator to stand undetected between the sensing field and the point of operation) This must be prevented by using additional safeguarding methods; usually, horizontal light curtains, or a physical barrier.
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Call Production Resources customer service to obtain an RMA. We need the following information to set up an RMA for replacement Wintriss boards:
Strain links produce a measurable electrical change when stretched or compressed. Strain links are bolted on the frame of the press or sometimes on the pitmans. On gap frame presses, links are usually located on the rear sides of the press. Alternatively, they can be mounted on the sides near the throat. When a gap frame press is under load, the rear of the frame will go into compression and the front (throat) into tension, which result in measurable electrical output from the strain links. On straight side presses, strain links are mounted on each column of the press, which are set in compression by tie rods. Under pressing load, the compression is relieved, which results in a measurable electrical change at the strain link. Occasionally, column mounting strain links on mono block straight sides won’t work properly, and strain links may be mounted on pitmans.
The strain links are connected to a load/tonnage monitor, which reads the strain link outputs and is calibrated to display that change as press tonnage. Tonnage display may be total only, left, right, or 4 corners on a straight side. Some devices also have the capability of measuring and displaying “reverse tonnage”. The calibration process allows the tonnage monitor to display in meaningful units (tons). At calibration, a load cell or cells are placed on the center of the bolster or directly under each pitman. When the press is cycled and the load cells are impacted, they display the impact force. The load monitor is then “calibrated” to match the load cell readout.
First determine what your objectives are since press automation controls are capable of multiple things. Die protection is usually a top concern, and almost all press automation controls include this feature. Load monitoring is another common consideration since it protects both the press and the tooling from overload. On variable speed presses, many press timing (stroke position) functions change relative to speed. Programmable limit switching (PLS) makes it easy to facilitate and remember these changes. It’s common to use a PLS to adjust feed, timing, pilot release, part blow off, airless lubrication timing, and top stop position. Many press automation controls offer other features such as: OSHA/ANSI-compliant clutch brake control, shut height and counterbalance control, and OEE monitoring.
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Die designers should work to minimize the potential for die damage by controlling how a part leaves the tool (avoiding blow off when possible), optimizing slug removal, and building in die sensors. Die protection controls are the next step. These controls can monitor multiple events and prevent or minimize die damage associated with:
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A good press safety audit should include verification that the press controls meet the current OSHA 1910.217 standards and the ANSI B11.1 standards.
The following are key elements to be verified:
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The traditional OEE calculation variables are:
OEE calculations are based on the premise that all production losses on machines and processes can be measured and quantified.
But, traditional OEE calculations come up short in many applications. While the Availability and Quality metrics can be universally applied to all machine types, difficulty arises when the traditional Performance metric is applied to discrete manufacturing processes where the true “ideal production rate” is more dependent on the parts being manufactured than the machine itself.
Consider the following OEE calculation example:
A machining center making “Part A” produces 6 parts per hour. After a job change the same machine produces “Part B” at a rate of 12 parts per hour. According to “traditional” OEE calculations, the “Part B” is running at twice the efficiency of “Part A”. However, let’s say that under ideal circumstances, our machining center is actually capable of producing “Part A” at a rate of 7 parts per hour, and the much simpler “Part B” at 30 parts per hour.
In actuality, the machine was running at 86% efficiency while making “Part A”, and only 40% efficiency for “Part B”.
The errors inherent in traditional OEE calculations can be manually factored out on a job-by-job basis, but this task becomes extremely difficult when trying to summarize overall equipment effectiveness over a longer period of time. In addition, the calculations required to properly “weight” jobs of varying length become very complex.
Instead of using a single ideal performance rating for each machine, ShopFloorConnect (SFC) software calculates OEE by applying a specific ideal rate for each job segment/machine combination.
In applications where a machine must make more than one cycle to produce a part, ShopFloorConnect automatically divides the ideal rate by the number of cycles required to make the part.
The ShopFloorConnect system keeps a running total of the actual parts produced by the machine, as well as the number of parts that could have been produced according to the ideal rates and multipliers. This allows SFC to accurately summarize performance over time, regardless of the lengths of the jobs that ran in the machine. SFC automatically “weights” the percentages according to job length. Most importantly SFC automates the process and provides easy to understand reports.
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The following measurements should be considered when calculating coil weights and production run time:
It’s important to ensure coil handling equipment is properly sized and not overloaded. Also consider safety and productivity features such as coil hold down arms for thicker materials or materials with considerable clock spring.
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