Windmill Software Ltd
Data Acquisition Intelligence

automating electroforming
August 2001

------------------------Monitor-------------------------
The Newsletter for PC-Based Data Acquisition and Control
Issue 37          www.windmill.co.uk         August 2001
--------------------ISSN 1472-0221----------------------

Welcome to the August Edition of Monitor. We hope you 
enjoy it, but should you wish to cancel your free 
subscription please visit 
http://www.windmill.co.uk/newsletter.html

This month, everything you ever wanted to know about 
electroforming and computerisation. A story 
illustrating how an automated control system increases 
safety, provides comprehensive records and improves the 
quality of the finished product.

CONTENTS
========
* Windmill News: Current monitoring device now available 
  from our Data Acquisition Catalogue
* Automating Electroforming Processes
  -- What is electroforming?
  -- The electroforming process
  -- Computerised control
     - Controlling the current density
     - Monitoring voltage to prevent overheating
     - Monitoring temperature and level
     - Controlling dosing
     - Laboratory control: ventilation for cyanide and 
       acid fumes
     - Equipment checking
     - Calculating the thickness of deposited metal on 
       complex shapes
     - Displaying and logging data
     - Future developments: web-based distance learning
* Data acquisition and control exhibitions
________________________________________________________

Windmill News: Current monitoring device now available 
over the Internet
________________________________________________________

Our on-line catalogue is now stocking a current 
measurement device for use with USB and ISA-bus units. 
This boxed unit sits outside the PC and accepts 8 current 
and 8 voltage inputs. For more details see
https://www.windmillsoft.com/daqshop/data-acquisition.html
________________________________________________________

Automating Electroforming Processes
________________________________________________________

Contents
========
-- What is Electroforming?
-- The Electroforming Process
-- Computerised Control
   - Controlling the Current Density
   - Monitoring Voltage to Prevent Overheating
   - Monitoring Temperature and Level
   - Controlling Dosing
   - Laboratory Control: Ventilation for Cyanide Fumes
   - Equipment Checking
   - Calculating the Thickness of Deposited Metal on 
     Complex Shapes
   - Displaying and Logging Data
   - Future Developments: Web-Based Distance Learning


What is Electroforming?
=======================
In electroforming a thick layer of metal is deposited 
either into a mould, or over a mandrel or model, which 
is usually later removed. This leaves a metallic object 
that is light, strong and an accurate replica. 

Electroforming is used in many industries, including in 
manufacturing precision components for the automotive 
and aerospace industries, in making fine jewellery and 
in exact reproduction of museum pieces.


The Electroforming Process
==========================
The mould or mandrel is placed in a tank of 
electroforming solution containing, for example, salts 
of nickel, silver or gold. The positive current from a 
power supply is connected to a pure metal plate at one 
end of the tank (the anode) and, at the other end of the 
tank, the negative current is connected to the piece of 
work to be electroformed (the cathode). The positive 
metallic ions are attracted to the negatively charged 
piece of work, where they are deposited. The metal in 
solution is replenished from the anode.


Computerised Control
====================
At its simplest, electroforming equipment can comprise 
just a small bath, a battery and manual calculations. 
However, for larger installations with several tanks and 
where precision is required, computer control comes into 
its own. The successful metal deposition depends on many 
factors, most of which can be monitored and controlled 
by a computer. A computerised system can also control 
the laboratory or workplace environment. It's perhaps 
easiest to illustrate by using a real example.

The University of Central England's School of Jewellery 
run eleven electrodeposition tanks. They control these 
tanks and log environmental data using a system provided 
by Biodata Ltd (www.microlink.co.uk), who employed the 
software expertise of Windmill Software.

                          *

CONTROLLING THE CURRENT DENSITY
Every electroforming solution has a range of upper and 
lower electrical power limits, between which a good 
result may be obtained. This is called the Current 
Density. Too little power and no metal will be 
deposited. Too much and the grains might brush off as a 
powder. The current density, measured in amps per square 
decimetre or amps per square foot, has therefore to be 
accurately measured and controlled. 

To calculate the current density required, we need to 
know the surface area of the object - a large object 
consumes more energy and has a higher resistance than a 
smaller one. The computer ensures that the optimum 
current density is applied throughout the process.

                          *

MONITORING VOLTAGE TO PREVENT OVERHEATING
The power supply's voltage drives the target current 
through the electroforming solution. The software 
monitors this voltage. Should it start to rise during 
the process it means that the resistance in the path of 
the current is increasing. This increase in resistance 
may be due to degradation of a contact point with the 
anode or cathode, which with quite high current passing 
through can lead to overheating. The software alerts 
operators and can automatically shut down the tank if 
necessary.

                          *

MONITORING TEMPERATURE AND LEVEL
The tank takes time to reach its operating temperature. 
The computer therefore starts heating the tanks before 
the start of the working day, so that it is ready when 
people arrive. The software monitors the tank for high 
or low temperatures, which indicate a failure of the 
heating controller. It also monitors the level of liquid 
in the tank - automatically turning the heating off if 
the liquid level falls.

                          *

CONTROLLING DOSING
Dosing pumps are used to replace chemicals that are 
consumed in the electrodeposition process. The gold 
alloy tank in the School of Jewellery, for example, has 
3 dosing pumps - each independently controlled. 

Chemicals are consumed on a current/time basis. The 
computer monitors the current through the tank and 
automatically doses the tank at regular ampere-minute 
intervals. However, the system also allows people to 
manually request a dose be applied, recording this 
event. There is also a push-button on the tank panel to 
disable automatic dosing. This interfaces with the 
computer through a digital input. The computer checks 
this digital input before proceeding with dosing - 
raising an alarm if the dosing is thus disabled. The 
software requires operators to acknowledge the alarm to 
confirm that dosing is suspended.

                          *

LABORATORY CONTROL: VENTILATION FOR CYANIDE FUMES
Because of the use of cyanide and acid based 
electroforming solutions, the workplace has to have 
adequate ventilation. In the School of Jewellery, the 
acid and cyanide lines are provided with fans to extract 
the air above each tank. These fans have a scheduled on-
off cycle, typically on for 5 minutes in every 20. They 
can also be switched on and off manually when required. 
The computer monitors pressure switches in the 
ventilation ducts to ensure that the fans are operating 
correctly. Any failure and it sounds an emergency alarm.

                          *

EQUIPMENT CHECKING
At the beginning of an electroforming process, the 
computer checks all the necessary equipment is in place. 
For example - it makes sure that the correct tank filter 
is connected. Should the filter be missing, or of the 
wrong type, the computer alerts operators, switches off 
the power to the filter and refuses to start the 
electroforming process.

The computer controls each tank's equipment, such as 
filters, agitators and aerators, through digital 
outputs. Should any of the equipment fail during the 
process, the computer sounds an alarm and if necessary 
shuts down the process for that tank.

          electroforming laboratory
          A corner of the University's
          new Electroforming Laboratory

                          *

CALCULATING THE THICKNESS OF DEPOSITED METAL ON COMPLEX 
SHAPES
It can be difficult to calculate the surface area of 
some complex shapes. This is important as the thickness 
of metal deposited is proportional to the current 
passing through a unit of surface area multiplied by 
time. However, if we have a test piece of work with a 
known surface area, the computer can measure the 
percentage of current going through the test piece. It 
can then calculate the amount of metal deposited on the 
test piece and therefore calculate the thickness of the 
plating material. This, providing the test piece is not 
located in a preferentially good position in the tank, 
will be less than or equal to the thickness of metal 
deposited on the work itself.

                          *

DISPLAYING AND LOGGING DATA
Each tank has its own display page with buttons for 
Running and Pausing. Alarm messages are displayed and 
tanks are shown in different colours for different alarm 
states. More detailed display pages are available, for 
example for heater and filter information. History 
graphs are also displayed. All data, including alarms 
and manual events, are logged to disk.

                          *

FUTURE DEVELOPMENTS: WEB-BASED DISTANCE LEARNING
Future developments for the School of Jewellery's system 
include a distance learning facility. Students will be 
able to view activity within the laboratory through a 
web browser and see the status of the various 
electrodeposition tanks. Using the web system, the 
lecturer will be able to remotely interact with the 
student.

                          *

This article has highlighted some of the advantages and 
uses of a computerised system. It increases safety - 
shutting down tanks should conditions not be right, not 
starting processes if the necessary equipment is not in 
place, sounding emergency alarms if cyanide extractor 
fans are not working correctly, and so on. It provides 
comprehensive records of the processes, logging all data 
to disk including information about tasks performed 
manually, any alarm conditions that occurred and the 
steps taken to remedy the situation. It also improves 
quality by ensuring optimum conditions.

For more information on a computerised electrodeposition 
system contact Windmill Software at 
[email protected]

Our thanks to Les Curtis, The School of Jewellery, 
University of Central England, for his help with this 
article. 
________________________________________________________

Exhibitions and Conferences
________________________________________________________

Upcoming data acquisition and control exhibitions 
include:

Automation 2001
4-6 September
Helsinki Fair Centre Finland
Comprises an extensive exhibition and seminar program.
http://www.finnexpo.fi/exhibition.asp?Id=600&code_language=en

ISA 2001
11-13 September
Houston Texas USA
The premier instrumentation, systems and automation 
conference in North America. This year features 700 
exhibitors, over 25 training courses and nearly 100 
seminars.
https://www.isa.org/events/1,1313,0,00.html

Automation Europe
18-20 September
Paris France
Billed as "the automated installation industrial 
performance event", companies will be exhibiting their 
automation, instrumentation, communication, monitoring, 
test and measurement equipment. 13000 visitors are 
expected to attend.
http://www.automationeurope.com/

Interkama 2001
24-28 September
Dusseldorf Germany
A biennial event showcasing industrial communication, 
automation and measurement.
http://www.interkama.de/

ISA 2001 UK
10-11 October 2001
Buton-Upon-Trent UK
ISA's first European instrumentation conference and 
exhibition comprises four conference sessions running 
parallel each day, plus a two-day exhibition. 
https://www.isa.org/

Manufacturing Week 2001
30 October - 1 November
NEC Birmingham UK
Includes 4 exhibitions: Drivers, Motors and Controls; 
Porduction; Automation and The Design Engineering Show.
http://www.manweek.co.uk/
________________________________________________________

* Copyright Windmill Software Ltd
* Reprinting permitted with this notice included
* For more articles see http://www.windmill.co.uk

We are happy for you to copy and distribute this 
newsletter, and use extracts from it on your own web site 
or publication, providing the above notice is 
included and a link back to our website is in place.

An archive of previous issues is at 
http://www.windmill.co.uk/newsletter.html
and an index of articles at 
http://www.windmill.co.uk/newsletter.html

Windmill Software Ltd, PO Box 58, North District Office,
Manchester, M8 8QR, UK
Telephone: +44 (0)161 833 2782
Facsimile: +44 (0)161 833 2190
E-mail: [email protected]
http://www.windmill.co.uk/
https://www.windmillsoft.com/



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