Electrochemical metal
processing perfected

Electrochemical metal processing perfected

ECM » TECHNOLOGY

Electrochemical metal processing (ECM)

Electrochemical machining (ECM) is a static or dynamic metal dissolution process that is described as the anodic dissolution of metals by electrochemical reactions.

ECM process application with stationary electrodes

The workpiece and the tool cathode are arranged stationary to each other. During electrochemical machining, the distance from one another increases because material is being removed from the workpiece.

ECM process with stationary tool electrode:

ECM static, v = 0 mm/s, Example: Deburring, rounding, smoothing
ECM static, v = 0 mm/s, Example: Creation of contours within the workpiece

ECM process application with dynamic electrodes

In the majority of applications, the workpiece is defined as stationary and the tool cathode is arranged to be movable relative to the workpiece via a machining axis. During electrochemical machining, the tool cathode moves toward the workpiece. The process is balanced when the material on the workpiece is removed at the same speed at which the tool cathode moves forward. The distance between both remains constant.

ECM process with dynamic tool electrode:

ECM dynamic, constant infeed speed of the cathode v = 0.5–100 mm/s, application: 3D spatial shapes, drilling

Precise electrochemical machining (PECM)

PECM is a technically advanced electrochemical machining process to produce very precise 3D shapes with the highest dimensional accuracy and best quality of the machined workpiece surface.

PECM process application with dual moving electrodes

This is an application in which the workpiece defined as stationary is picked up. The tool cathode is arranged to be movable relative to the workpiece via an NC axis and an oscillating mechanism. During the PECM process, the tool cathode moves toward the workpiece at a constant velocity of v1. The tool cathode is connected to the NC axis via an oscillating mechanism. The oscillator produces one of the + v2 and – v1 forward stroke and return stroke superimposed with v1. The superimposed stroke causes the balanced gap to shrink for milliseconds. At the moment of the minimum gap, the process pulse generator ignites and also switches one or more current pulses to the micro gap for milliseconds. The effect is that very high and concentrated directed current peaks are introduced into the micro-gap by the greatly reduced electrical resistance of the micro-gap. This concentrated current pulse produces the best workpiece surfaces. The proximity of the cathode to the workpiece causes the negative of the cathode contour to be reproduced very precisely on the workpiece surface.

PECM process application with dual dynamic work electrode:

PECM dynamic, constant infeed speed v1 of the cathode with pulsating superposition v2 –> The synchronized current pulse occurs with minimum gap.

stoba Customized Machinery not only supplies PECM machines for the production of tool applications in small unit volumes, but primarily for the production of high numbers of workpieces in fully automated production lines with integrated pre- and post-treatment processes for the workpieces.

ECM » APPLICATIONS

Process applications of ECM and PECM technology with stationary electrodes

Electrochemical deburring of edges

This describes the ECM process for deburring workpiece edges at and on the inside of machined workpieces.

Special features of electrochemical deburring:

  • Easy adjustment of the tools (cathodes) even with internal deburring
  • Contactless process
  • Cold process
  • Fast process: The deburring time is in the range of 15 seconds.
  • The process only removes the material of the workpiece, not the tool.

Electrochemical rounding of edges

This process works in a similar fashion to the deburring process, but has a higher degree of material removal at the workpiece edges to precisely round them.

Special features of electrochemical rounding:

  • Fast process: The process time for rounding workpiece edges, the deburring time, is within a range of 20–45 seconds.
  • The longer the process time, the stronger the edge rounding
  • The production of an edge rounding of one (1) millimeters is cost-effective.

Electrochemical smoothing and polishing of workpiece surfaces

Electrochemical polishing makes use of the fact that during electrochemical removal, the material particles are removed at the atomic level. Tedious manual polishing and smoothing work on the workpiece can be easily performed electrochemically and quickly.

Special features of electrochemical polishing:

  • Cost-effective in high unit volumes, since processing device with adapted tool cathode is needed for polishing
  • Fast process: The process time for smoothing and polishing is in the range of a few seconds.

Manufacturing shapes and contours with static ECM machining

With this ECM process, shapes are created on the workpiece or inside the workpiece. The process is static, i.e. neither the workpiece nor the tool move during this processing. The tool cathode is brought to the specified position for processing. After switching on the ECM process, the cathode takes effect and removes workpiece material around it. This results in a shape which is similar to the cathode in the workpiece.

Special features of ECM shaping:

  • Easy adjustment of tools (cathodes) even in positions inside the workpiece
  • The processing of the shapes takes place without the formation of burrs.
  • All edges are rounded.
  • All workpiece surfaces are smooth and free of microcracks or other influences.
  • The process for producing the chamber in an injection nozzle for automobile engines takes about 90–120 seconds. Due to the simple possibility to process many workpieces at the same time, the process time does not change. Thus for example, the average process time for processing 30 to 40 injection nozzles is less than 3 seconds per workpiece.
  • No restrictions on hardened or tempered workpieces

Process applications of ECM and PECM technology with dynamic electrodes

ECM machining

ECM machining is used to form spatial shapes of greater depth than is possible with the static contour machining process. The precision of the machined spatial shape is much higher than in static molding. The term precision in this case particularly includes imaging accuracy, dimensional accuracy, repeat accuracy, sharp edges, and the surface quality, etc.

During ECM machining, the tool cathode usually moves towards the workpiece. A constant gap distance of 200-500 μm appears during a balanced process. The removing DC or pulsed DC depends on the effective area of the shape and on the infeed rate of the tool cathode. The current can assume values ranging from a few amps to several thousand amps in applications.

Special features of ECM machining:

  • Constant infeed motion, DC or pulsed DC
  • The processing of the shapes takes place without the formation of burrs
  • All edges and slightly rounded.
  • All workpiece surfaces are smooth and free of microcracks or other influences.
  • Infeed speeds are in the range of approx. 0.5 to more than 100 mm/min. In the event that a cathode is expected to produce a shape in a tempered steel block, the infeed speed is about 4 mm/min.
  • ECM machining is used to create spatial shapes such as dies, engine blades, engine parts, or medical implants, etc.
  • Another application example is the drilling of holes in the event that they require especially good and notch-free surfaces or the hole profile may not be able to be circularly formed.
  • 3D spatial shapes can be manufactured with shape and repeat accuracies of ± 200–500 µm.

PECM machining

PECM machining is a modified process of ECM machining It is also used to manufacture spatial shapes.

As with ECM machining, during PECM the cathode also moves with a constant infeed speed toward the workpiece. In addition however, the cathode is set up on an oscillator, which accelerates it forward and retracts it in the direction of the constant infeed motion. The forward and backward movement takes place with a frequency of 50 Hz.

During the forward movement, the gap between the cathode and the workpiece decreases from a few hundred to only a few micrometers. At the moment when the gap distance is at its smallest, the machine control ignites the generator. In a synchronous fashion, this switches one or more current pulses onto the gap. During the retraction phase of the vibration, the generator is switched off, the gap opens, and is traversed by electrolyte, which washes out removal products and heat.

Particularly precise shapes can be produced with PECM machining, with further improved imaging accuracy, dimensional accuracy, repeat accuracy, sharp edges, and surface quality, etc.

The pulse current can assume values ranging from a few to several thousand amps in applications.

Special features of PECM machining:

  • Constant infeed motion with superimposed cathode vibration, synchronized pulsed DC
  • The processing of the shapes takes place without the formation of burrs.
  • All edges have maximum sharp edge.
  • All workpiece surfaces are smooth and free of microcracks or other influences.
  • Infeed speeds are on average 0.01–0.1 mm/min.
  • The PECM process is used to create spatial shapes such as dies, engine blades, engine parts, and medical implants, etc.
  • 3D spatial shapes can be manufactured with shape and repeat accuracies of plus/minus 10–50 μm.

ECM » PRODUCTS

The portfolio of stoba Customized Machinery includes a range of machines for electrochemical machining optimized to meet the needs of the customer. Customized concepts ranging from the compact entry-level model, to modular production systems, to fully automated complete solutions are implemented.

ECM Systems

ECM Machine – alpha basic

The attractive entry-level model for the world of ECM deburring technology

  • Control: Siemens, Beckhoff
  • Ergonomic and clear operating concept
  • Machining area D x W: 600 x 1050 mm
  • Generator: Up to 1,000 A bei 58 V (with or without pulse function)
  • Attractive entry-level variant suitable for small unit volumes

ECM Machine – alpha mono

The flexible all-rounder for electrochemical deburring and machining

  • Modular machine concept – can be automated after start-up
  • Control: Siemens, Beckhoff
  • Variants adapted to requirements
  • Manually operable or automation from all three sides
  • Machining area D x W: 1050 x 1050 mm
  • Generator: up to 1,200 A at 58 V (with or without pulse function)

ECM Machine – alpha duo

The dual station solution for the reduction of nonproductive time when deburring and machining

  • Control: Siemens, Beckhoff
  • Flexible machine solution for a wide variety of tasks
  • Possible with one or two machining areas
  • Outstanding suitability for large and long components
  • Manually operable or adaptable automation solutions
  • Generator: up to 3,000 A at 58 V (with or without pulse function)

ECM Machine – alpha series automated

stoba ECM systems with adapted automation solutions for multi-shift operations

  • System comprised of proven standard modules
  • Integrated process chain of infeed transport, ECM, cleaning, drying, and removal
  • Expansion levels based on the production volume
  • Achieving cost-effective cycle times
  • Layout adapted to space conditions
  • Process integration and support from a single source

ECM Machine – delta 3D-ECM

CAM-assisted 6-axis robot for cost-effective ECM deburring tasks, e.g. for hydraulic blocks

  • Effective in smaller unit volumes as well, e.g. large pump housing from the oil and gas industry
  • Precise deburring results with high repeat accuracy
  • CAD/CAM-assisted ECM processing strategy
  • Integrated cathode changer for executing various deburring tasks
  • Determination of the workpiece zero point via the 3D scanning system, e.g. Renishaw OMP 40
  • Generator: up to 3,000 A at 58 V (with or without pulse function)

ECM machining systems

ECM machining modules

For integration into standard machines or stations

  • NC-axis module with position encoder for installation in standard alpha, beta, or delta ECM machines.
  • Modules configured and designed for precise ECM machine processing.
  • Operation with one axis or multi-axis
  • Available for manual or fully automatic operation
  • Suitability for the generation of spatial shapes with smaller cross-sectional area e.g. for drilling holes
  • NC-controlled precision vertical axis with constant infeed
  • Basic structure of the axle module made of granite or steel
  • Zero-point clamping system as interface for the cathode holder
  • Generator: up to 10,000 A at 15 V DC with synchronized pulse function
  • Control: Siemens

ECM machining equipment

Single or multi-axis machining equipment for ECM machining processes

  • ECM machining equipment with vertical, horizontal, and angled vertical axes.
  • Suitable for the generation of spatial shapes with larger cross-sectional area e.g. dies, engine blades, implants, etc.
  • NC-controlled precision vertical axes with constant infeed
  • Synchronized axis operation during multi-axis operation
  • Basic structure of the machine frame made of granite and steel
  • Clamping plates for ECM device and cathodes
  • Infeed forces between 25 and 50 kN per axis, depending on the application.
  • Generator: up to 10,000 A at 30 V DC with or without pulse function
  • Control: Beckhoff, Siemens

PECM machining systems

PECM Machine – sigma

The precise machining system for high reproduction accuracy with optimal surface quality

  • Suitable for high-precision shapes in a minimum of time
  • NC-controlled precision machining axis with integrated mechanical oscillation
  • Granite machine construction
  • Zero-point clamping system as interface for the cathode holder
  • Generator: up to 10,000 A at 15 V DC with integrated pulse function
  • Control: Machine and process control from the Beckhoff company
  • Version as two-station system for manual or linked automated operation

PECM machine – beta semi-automatic

The cell solution for integrated such as ECM deburring, machining, cleaning, drying, preserving

  • This machine contains the entire process chain in a compact space
  • Integrated pallet conveyor with 11 workpiece positions
  • The pallet moves from processing station to processing station
  • Reduced workload for operating staff
  • Process integration and support from a single source
  • Control: Siemens

beta – ECM system solutions

The top of the line all-in-one concept

  • The fully automated system solution for high-production ECM and PECM processing. The system contains the ECM/PCM processes, automation, measurement technology, cleaning technology, drying, marking, and labelling
  • Central workpiece infeed and output
  • High-production system solution with up to 14 deburring stations
  • Integration of PECM machining possible
  • Modular design with the option of incremental expansion
  • Achieving cost-effective cycle times
  • Process integration and support from a single source
  • Control: Siemens

ECM » Subcontracting

ECM/PECM technology – the area of specialty of stoba Customized Machinery

stoba Customized Machinery stands for professional customized machinery. This not only includes the construction and sale of the machine technology, but also the process technology. stoba Customized Machinery plays an essential role as the sole supplier of machines with ECM/PECM technology. Therefore, the stoba group of companies uses the actual machines and processes in-house as well. Of course, this includes sister companies based around the world who use the stoba Customized Machinery ECM process in all variants as a core process for their own production. The entire stoba group of companies strives to further develop the ECM/PECM process and make it stable for mass production, i.e. to generate optimal process development and the highest series stability of the components.

ECM processes as subcontracting offer security

If you as a customer are unsure whether ECM is the right process for your manufacturing, then we’ll offer to carry out the ECM processing on commission.

Therefore you’re initially only investing in a suitable processing device as well as necessary cathodes and we carry out the subcontracting for you.

Unit volumes of over 100,000 parts per year

As a machine builder, we only have capacity for limited unit volumes.

If the quantity you require exceeds 100,000 parts per year, we gladly hand over the process to our sister companies who, as production professionals, will take care of the processing.

Complete manufacturing by the stoba group of companies

Would you like us to take on an even higher level of vertical integration and completely finish the workpiece in question? Yes, that’s possible. Contact us. We gladly accompany you during production development and thus bring our expert knowledge to bear early on.