ronnell | CA Machine Tools - Metalworking Blog

Punch Press

Punch presses are used when processes require hole to be punched in material. From small and manual to large, complex CNC machines, punch presses vary depending on the scale of the operation. Most punch presses have either a portal (bridge) frame or a “C” type frame. The following are some of the criteria used to determine what type of punch press you need:

Size of work area

Drive type

Force rating

Weight of the workpiece

Drive Type

The drive type is the system used to deliver force to the ram. There are several different types used for different purposes.

Flywheel

BrownBoggsPunchPress 1 151x300 Punch Press — Flywheel Punch Press

A flywheel is a constantly rotating machine. With flywheel, adjusting the speed during the process is difficult. With the advent of newer systems, these types of presses are no longer common.

Mechanical

331010 4d03821455b8de728ccae9ae25069684 252x300 Punch Press — Mechanical Punch Press

There are two types of mechanical punches: full revolution and part revolution. The full revolution requires the crankshaft to rotate a full turn before coming to a stop. The full turn is necessary because specific slots must catch raised keys in order to stop the rotation. More advanced machines use a part revolution which works with a braking system.

Hydraulic

These presses use a hydraulic cylinder are can be controlled by a valve or by a valve and feedback system. Valve controlled hydraulic presses let the ram stroke up and down in a one-stroke operation. The valve and feedback system offers control proportionally so the stroke can be set to fixed points. This system provides more flexibility and increases punching rates.

Servo drive turret

m2048st pic 001 300x160 Punch Press — Servo Drive Turret Punch Press

This type of punch press uses twin AC servo drives connected to the drive shaft. This system is effective because it has the speed of hydraulic systems as well as the control provided with clutches and brakes. Although this type of punch matches the speed of hydraulic systems, it has no hydraulic parts which means it needs less maintenance. Servo drives also reuse the energy that gets generated during deceleration. This lessens the amount of power needed to run the machine.

The Brake Press

The brake press, also known as press brakes are very useful shaping sheet metal. Typically they work with a table below which holds the die and a moveable beam above where the punch is located. There are several types of brake presses available and they are described by the types of force applied in the process.

Mechanical Press – A clutch is used along with a flywheel to operate a crank. Mechanical presses are known for their speed and accuracy.

Mechanical Press1 300x264 The Brake Press — Mechanical Press

Hydraulic Press – Uses two hydraulic cylinders located on the sides of the press. They move the upper beam.

Electro Hydraulic Press large 1 250x300 The Brake Press — Electro Hydraulic Press

Servo-electric Press – Exerts force by driving a belt drive or ballscrew with a servo-motor (a motor with encoders to provide accurate positioning and speed).

546802 300x201 The Brake Press — Servo-electric Turret Punch Press

Pneumatic Press – Uses air pressure to provide force.

PNEUMATIC PRESS TO PIERCE HOLE Medium Web view 198x300 The Brake Press — Pneumatic Press

Applications

Mechanical presses have long been the dominant type in the world of machining. But since the 1950s, hydraulic presses have become the most popular as a result of advances in hydraulic and computer technologies. Now, hydraulic presses are known to be very reliable and accurate. They are also considered a safe option because the ram’s motion can be stopped much easier than that of flywheel-driven mechanical presses. Servo-electric and pneumatic presses are ideal for processes requiring lower amounts of force (tonnage).

Novel Use For a Water Jet

Water jets are great for processing metals for food-related uses. But what about food itself? Paprima’s Ultra-High Pressure water jet is a great method for cutting food for several reasons. Water jets are much more hygenic than traditional methods because they don’t involve blades which have been known to transfer bacteria and pathogens onto food products. And this particular water jet uses a continuous stream of drinking water rather than mixing water with an abrasive. The UHP water jet has an opening of about .004″ which is small enough to cut delicate foods producing a clean cut with no bruising.

The nozzle on the UHP moves water at 3 times the speed of sound providing extreme cutting power. The diamond nozzle should be able to last approximately 3 months being used continuously.

APPLE HALF CIMG0998 300x246 Novel Use For a Water Jet — UHP Water Jet cutting apples

Milling 101

Milling is basically the process of removing material. It began centuries ago as a way to process grains using stones.

Eventually, it also came to include metal processing with rotating cutting tools. As milling evolved, the array of tools that could be employed increased greatly as did the precision. Choosing the right tool and the proper machining parameters in milling is essential to achieve an optimum outcome.

Types of Milling

Face Milling – Used for making flat surfaces. The cutters usually have a single row of inserts. The tools used for face milling will preferably have a lead angle for long tool life.

Face Milling Machine1 300x300 Milling 101 — Face Milling Machine

Slot Milling – Used to produce slot and channels. Mainly, slot milling is done with either a disk mill or an end mill. Disk mills are usually used for operations that are perpendicular to the spindle rotation. Types of disk mills are high-speed steel, brazed carbide, and indexable-insert-based. These will be used for operations perpendicular to the spindle rotation. End mills are used when the slot needed must be parallel to the spindle rotation and often result in poorer quality due to poor chip formation and other factors. End mills have a smaller tool diameter and greater length which causes them to be less stable than all other milling cutters.

PVC Window Water Slot Milling Machine Four Axis LXC01 4 300x240 Milling 101 — PVC Window Water Slot Milling Machine

Periphery Milling – Creates a primary surface that is parallel to the spindle rotation. Often times, there is also a secondary surface generated. Types of periphery milling cutters include: solid carbide, high-speed steel, and indexable-insert-based.

Specialty Applications

There are additional types of milling that can be used for specific jobs. Here are a couple:

Ramping – Used for making angled surfaces or for making a pocket at the point of entry.

Helical and Circular Interpolation – Used to create a cylindrical surface or to make entry points that can be used later.

Advantages of Waterjets

When fabricating metal products, waterjets offer many advantages over other cutting machines. One benefit is their ability to make precise cuts without heat. When cutting machines expel heat during the cutting process, the chance of altering or damaging the material’s intrinsic properties increases. With waterjets, heat-sensitive materials can be processed without worrying about incidental damage.

Another benefit of waterjets is their capability of cutting complex and intricate designs. The width of the cut can easily be altered by adjusting the type/size of abrasive used as well as the nozzle. This allows the machinist to make very detailed cuts with an accuracy of about 0.13mm.

Advantages of Waterjets

Waterjet cutting complex pattern

Also beneficial is the efficiency of waterjets. They maximize efficiency in a number of ways. Considered a “green” technology”, waterjets do not create any hazardous waste. Additionally, they can save more material than other, less precise cutting methods because they are so precise. This allows them to cut only what is needed, keeping the width to a minimum. They are also efficient because they don’t need much water to operate. And the water used can be recycled with a closed-looped system. The garnet abrasive used is non-toxic and can also be recycled.

Another advantage is the lack of airborne chemicals that are common to other cutting methods. With waterjets, there are no fumes or contaminants from cutting potentially hazardous materials such as fiberglass.

Food-Grade Stainless Steel Finishing

In the machining world, “food-grade” is a term that refers to a specific type of finish for metal products. Food-grade means that the surfaces of the metals used are safe enough and clean enough to process food on and also fairly easy to clean after using. For this reason, food-grade metals must not contain divots or grooves as those will likely allow bacteria to grow. The metals must also be able to withstand the corrosive effects from processing food as well as from cleaning with chemical solutions on the surfaces.

Most often, a food-grade finish is one with a finish at the high end of Number 4 (brushed). To achieve this finish, a high-grit abrasive ranging from 150 to 220 should be used. The surface roughness average (Ra) measured in micro-inches will dictate the success of the finish. For the majority of food-grade finishes, 60-36 Ra is acceptable. But if the surfaces will be used for dairy products (milk, etc.), the finish should be finer since these products carry more bacteria and spoil quickly.

Choosing the Right Tool

Finishers/Wraparound Pipe Belt Sanders

Food Grade Stainless Steel Finishing

Flex Pipe Belt Sander LBR 1506 VRA

These are multi-tasking machines that can perform several functions. These machines can grind flat surfaces and removes weld seams. The sanding belts on these machines can also follow the specific contours of pipes.

Linear Finishers

Food Grade Stainless Steel Finishing

BD-300 Linear Finisher

These types of machines are suitable for long, flat surfaces without streaking as well as finishing in corners. For brushing, deburring, and blending, these are the machines to use.

Finger Belt Sanders/Wraparound Pipe Sanders

Food Grade Stainless Steel Finishing

Flex LBS 1105VE Finger Belt Sander

These machines are specifically suited to perform one task. They are perfect for tight spaces and angles because. They use narrow abrasives and are good in smaller areas.