HOW TO PURCHASE THE BEST HYDRAULIC PRESS ...

HOW TO PURCHASE THE BEST HYDRAULIC PRESS ...

Today's hydraulic presses are faster, more reliable than ever, and can perform various tasks within their tonnage range, providing excellent versatility. They are also straightforward and cost-effective compared to mechanical presses of similar sizes. With fewer moving parts, which are fully lubricated in a flow of pressurized oil, maintenance becomes less of a chore. These parts are generally standard, affordable, off-the-shelf components, making replacements easier and cost-effective. This translates to more operational time and reduced maintenance costs. Additionally, hydraulic presses offer easy tonnage adjustments and better tonnage control throughout the press stroke, widening your range of applications. If you're considering opting for a hydraulic press, here are some vital points to keep in mind:

View Details

Selecting Your Press Tonnage

The first consideration when buying a hydraulic press is the tonnage required. The required tonnage to perform a job is the same for both hydraulic and mechanical presses. The same calculation methods are used to determine the tonnage for both types. In certain tasks like deep drawing, a hydraulic press's full power stroke can reduce the required tonnage, but there are no scenarios where a hydraulic press demands more tonnage than a mechanical press. Often, press tonnage is assigned based on guesswork. For example, if a job works well on a 100-ton mechanical press, it is left there for the job's duration. With a hydraulic press, however, you can adjust the tonnage quickly, fine-tuning the press to the precise tonnage needed for each job.

How The Press Affects the Job

After deciding the required tonnage, it's essential to understand how the stroke will impact the work. Generally, there is no difference between hydraulic and mechanical presses in most applications. There are some exceptions: Drop hammers and certain mechanical presses may perform better on soft materials like jewelry pieces. Conversely, hydraulic presses are superior in deep drawing applications due to their full power stroke. Overall, applying 100 tons of hydraulic force will yield results similar to a mechanical press given the same tooling. Shear in the dies affects blanking tonnage for hydraulic and mechanical presses similarly.

What Type of Press is Best for You

Next, consider which hydraulic press type suits your application best. Open-gap presses allow easy access from three sides, while 4-column presses ensure even pressure distribution. Straight-side presses offer the required rigidity for off-center loading in applications like progressive dies. Remember, the more critical the work and the tighter the tolerances, the greater the reserve tonnage capacity should be.

After choosing the basic type, explore the available options. Many hydraulic press builders provide various accessories, such as:

• Distance reversal limit switches
• Pressure reversal hydraulic switches
• Automatic (continuous) cycling
• Dwell timers
• Sliding bolsters and rotary index tables
• Die cushions
• Ejection cylinders or knockouts
• Electronic light curtains and other safety features
• Touch screen controls
• Servo system feedback for precise stroke control

It is crucial to determine the quality needed for your work. The quality of hydraulic presses can vary significantly. Light-duty presses can momentarily "spank" the work and reverse, while heavy-duty machines are designed for general-purpose metalworking.

Frame: Evaluate construction rigidity, bolster thickness, and dimensional capacity.
Cylinder: Examine the diameter, construction quality, manufacturer, and serviceability.
Maximum system pressure: Check the psi at which the press achieves full tonnage, typically ranging between 1000 to 3000 psi.
Horsepower: Consider the pressing stroke's duration, length, and speed to determine required horsepower.
Speed: Assess the speed offered by each hydraulic press.

Buyer Beware

Several pitfalls warrant caution when selecting a hydraulic press:

• Speed: Hydraulic presses are generally slower than mechanical ones. If speed is crucial and the application and material feed stroke are fixed, a mechanical press may be a better choice.
• Stroke depth: Using a limit switch can result in a stroke depth control error margin of around .020". Many hydraulic presses can reverse at a preselected pressure, ensuring uniform parts. For absolute stroke depth accuracy, "kiss" blocks may be needed in the tooling.
• Automatic feeding equipment: Hydraulic presses require external or auxiliary power to feed stock. Ensure the feeder has its own power and is integrated with the press control system. Luckily, self-powered feeding systems like roll feeds, hitch feeds, and air feeds are increasingly available.
• Shock after breakthrough in blanking: Both mechanical and hydraulic presses face this challenge. However, hydraulic systems must be isolated from decompression shocks, which can affect lines and fittings if the system lacks an anti-shock feature.

Do Your Homework

As with any major purchase, do your homework. Once you decide to go hydraulic, consider the factors discussed above to ensure you find the best solution for your specific application. Partner with a vendor who offers excellent communication and support, engineering expertise, and custom-build capabilities, ensuring long-term success.

Source:
Greenerd Press & Machine Company, Inc.
www.greenerd.com

What to Consider when Choosing a Hydraulic Press