Resistance Welding of Butted Rings EDIT.pub
Contents
1. Power Source Electrode Assembly Timne eeure Optional Variac Welder Diagram neen CirCuit Diagramm a How Resistance Works Resistance Current Voltage Ihe Weil Cycle nee en Squeeze Time Weld Time Hold Time Welder Variables ccceceseccceecceecceeececueees Electrode Position Weld Duration Material Vaniables ian a page 11 Cleanliness Wire Diameter ASPEC ERAU Oona EE ee page 12 Cuts Operator Varrables antenne page 13 Pressure Electrode Maintenance Commonly Used Melusine page 14 Iron amp Steel Brass amp Bronze Niobe Titan een page 15 Aluminum Copper Silver amp Gold VES OE Weldsan sinne dee du tele page 16 Solid Welds Upset Welds Flash Welds Bad VV GS Scio es ge ates sense page 17 Examples OT WeldedRinssi a 2e isn nannte page 18 Wed Strenge ee Been ee a il page 19 B75 0 Ce 0 0 0a ee ee a page 20 Introduction This document is intended to be a practical guide to welding butted rings using a resistance welder It is being distributed as a companion to the resistance welder kit designed by the author and distributed through TheRingLord com s website The information pre sented throughout this document will be referring specifically to those resistance welders but may also apply to resistance welders in general This is not a user manual please take the time to read the instruc tions and safety precautions in the original equipment manufacture2. a 2X Mounting arms b 2X Brackets c 4X M6 nuts amp bolts d 2X M8 nuts e 2X SH16516 rings f 2X copper terminals g 2X 6 copper cable h 2X electrodes 1 4X insulating washers 3 Timing assembly a Timer b Foot switch c Power cord d 4X clear terminals e 10 32 bolt f 2X yellow terminals 4 1 pair heat resistant gloves 5 Sample welded rings 6 OEM Manual 7 Resistance Welding of Butted Rings booklet Setting Up Your Welder Power Source The power source for the welder is a commercially available re sistance welder transformer The welder has been tested before ship ping and the test welded rings have been included with your kit Many of the OEM parts have not been assembled or included with your resistance welding kit because they are unusable for welding rings For further information or questions review the OEM user manual for this welder that shipped with your welding kit Due to safety concerns we have not modified the electrical circuit in any way You may install the timing circuit on the welder and re move the OEM switch if you choose to do so Instructions are pro vided in this document Electrode Assembly Please note that the OEM electrode assembly is not included with the welding kit A new electrode assembly has been purpose built for TheRingLord com and has been mounted to the front of the welder This electrode assembly is intended to be adjustable for welding butted rings with inner diamete
3. normally be resolved by proper electrode adjustment They are not much weaker but can chafe and are an eyesore in jewelry because they are off round A slight misalignment or burr can often be flattened by squeezing it be tween the jaws of smooth faced pliers See page 18 fig 2 5 Burnt welds are caused by too much weld time without sufficient pressure In these welds the metal has been overheated and begun to oxidize this causes at least a portion of the weld area to turn to slag The metal in the weld area will usually sag or crumble In extreme cases a large section of the ring can liquefy and spray droplets of molten metal If the welds are only slightly burnt and not yet brittle then they may be used for applications where appearance is not a concern See page 18 fig 2 6 17 Examples of Welded Rings Fig 2 1 Fig 2 2 A typical solid welded ring A typical upset welded ring Before and after strength test Before and after strength test Fig 2 3 Fig 2 4 A typical flash welded ring A typical tack welded ring Before and after strength test Before and after strength test Fig 2 5 Fig 2 6 OO OO A typical misaligned welded ring A typical burnt welded ring Before and after strength test Before and after strength test Denotes strength tested rings which were badly deformed and required flattening to improve image quality 18 Weld Strength Weld strength can be tested by pulling and twisting the ring be tw
4. the timer relay the welder will probably not function below a cer tain voltage Welder Diagram Fig 1 1 Warning Label Circuit Diagram Fig 1 2 AC Hot Timer AC Neutral l Potentiometer Relay Foot Switch AC Hot Load Transtormer Grounc sround Electrodes AC Neutral l How Resistance Works Resistance Resistance measured in Ohms is the opposition of an electrical circuit to the flow of current It is calculated by dividing the voltage by the current Resistance is what heats the ring so it is very impor tant that the point in the circuit with the highest resistance is the butted joint of the ring Current Current measured in Amperes and abbreviated Amps or just A is the amount of electricity that is flowing through an electrical circuit A standard household socket in North America can supply 15A but it takes several hundreds or thousands of Amps to make a resistance weld The welder power source is a transformer that increases the am perage of the electricity to a level where the resistance can heat the ring to welding temperature Voltage Voltage measured in Volts and abbreviated V is the force that causes the current to flow When the amperage is increased by the transformer the voltage decreases inversely Increasing or decreasing the voltage will also increase or decrease the heat of the weld The Weld Cycle Squeeze Time A resistance weld is separated into 3 distinct phases
5. weld easily The corrosion resistance of stainless steel will be somewhat reduced during the welding process but can be mostly restored by polishing off the oxide layer Resistance welds made in steel or iron should be stronger than the original wire Steel alloys with a large amount of carbon may need special heat treating after they have been welded otherwise the heat affected zone can become very brittle The fumes produced from welding galvanized or zinc chromate plated steel are toxic and will make you very sick Do not weld these materials Brass amp Bronze Brass and bronze are copper alloys Copper is a very low resis tance metal which is why the welder s electrodes are made from it Very good resistance welds can be made with most copper alloys but the weld timer will need to be set for shorter periods compared to iron alloys Using a Variac to decrease the voltage is useful for smaller wire sizes With practice the welds in either metal can be made stronger than the original wire but in many cases it s more practical to make welds that are just strong enough for the application 14 Titanium amp Niobium Titanium and niobium are reactive metals When heated in air they readily form brittle oxides with atmospheric oxygen In most welding processes they cannot be welded unless they are covered with inert gases such as argon or helium Resistance welding is an exception By using very fast weld times and high pressure the m
6. First there is the squeeze time This is the period of time just before current is ap plied when the operator presses the ring against the electrodes with a constant pressure Weld Time The second phase is the weld time During this phase the operator maintains the pressure on the ring while applying current This heats the metal of the ring to a plastic or liquid state and forces the ends to gether creating the weld Hold Time The third and final phase is the hold time This phase begins as soon as the current has stopped flowing through the ring During this phase the operator must continue to maintain pressure against the ring until the metal has cooled to the point where it is solid again Welder Variables Electrode Position The position of the electrodes is adjusted individually keeping them as symmetrical as possible You can change both the angle at which the electrodes contact the ring and the distance between the electrodes It s important to angle the electrodes so that when pressure is ap plied most of the force presses the ring against them but a significant fraction also presses the ends of the ring together The greater the distance between the electrodes the higher the re sistance in the wire will be and the less concentrated the heat will be on the butted area to be welded This can be useful for some ring sizes but will create a larger heat affected zone HAZ on the ring In general it is best to keep the gap
7. are re quired to get good solid welds See page 18 fig 2 1 Upset Welds Upset welds are the preferred welds for most applications they are usually stronger than the wire the ring is made from To make an upset weld you must ensure that there is enough heat and pressure so that the metal becomes plastic when it is forced together and creates a widened upset area around the welded joint During this process any oxidation is squeezed outwards from the weld area in a similar man ner to forge welding See page 18 fig 2 2 Flash welds Flash welds are a result of the upset area liquefying due to extra heat and pressure and forming a large circular burr known as flash This is a strong weld in most metals but the ring will be more oval shaped and the flash may chafe against skin Usually the flash can be smoothed off to an acceptable level See page 18 fig 2 3 16 Bad Welds There are many types of bad welds and combinations thereof I ve listed a few of the most common They usually have a major draw back for typical uses Tack welds look similar to a solid weld but are more brittle They are caused either by contamination of the weld or by not enough weld heat Tack welds may be acceptable for some non strength critical ap plications Trying to re weld tack welded rings seldom results in a good bond See page 18 fig 2 4 Misaligned welds occur when the ends slip away from each other during the weld time Alignment problems can
8. between electrodes relatively small but wide enough that the electrodes don t become overheated The gap can be precisely adjusted using shims Weld Duration Weld duration is adjusted via the potentiometer knob on the timer Increasing the amount of time enables the operator to heat larger rings to their welding temperature Decreasing the time gives more control for smaller rings and less resistive metals I suggest marking the positions of your most frequently used settings 10 Material Variables Cleanliness Any contaminants on the ring s cut area such as dust oil or ox ides can interfere with getting a good weld In some cases contami nants can prevent any welding or cause the welds to become very brittle Freshly cut rings are usually free of contaminants but saw cut or machine cut rings may have residual oil or grease from lubrication Ultrasonic cleaners are the best way to remove contaminants from cuts Washing with detergent and water is also usually effective Conversely purposely contaminating a weld joint can be used beneficially to create more resistance or prevent oxidation in difficult to weld metals This is an advanced technique and specific details are usually guarded as trade secrets Wire Diameter The thickness of the wire affects the resistance thinner wire will have more resistance and therefore require less heat and time to weld Thicker wire transfers more heat away from the weld area and is stronger r
9. een two pairs of pliers until it breaks or deforms Always test the strength of your welds after changing a welder or material variable When making armor it is a good idea to periodically test the strength of your welds while you work If the ring breaks on the weld with no deformation of the ring then it is less strong than the yield strength of the wire This indicates a tack weld which usually has much less than 50 of the strength of the wire If the ring breaks on the weld with some deformation of the ring then the weld is stronger than the yield strength of the wire but less strong than the ultimate tensile strength of the wire This is typical for solid welds in most metals and flash welds in Ti and Nb These welds are fine for some applications in commonly welded alloys they will generally have between 60 90 of the strength of the strongest welds If the ring breaks in a spot that is not on the weld then the weld is stronger than the ultimate tensile strength of the wire This is the strongest that any welded ring can be the weld strength is 100 or higher The ring will usually break on the wire directly adjacent to where it has been clamped 19 Conclusion Welding is a complex process which requires practice and skill I have compiled most of the basic principles of resistance welding as they apply to butted rings but there is much more to learn that falls outside the scope of this document TheRingLord com s discussion f
10. equiring more heat and pressure to weld properly Trying to weld wire larger than 12g 1s possible but can result in problems such as operator fatigue damaged electrodes and shortened welder life 11 Aspect Ratio The aspect ratio AR of a ring is the ratio of its inner diameter to the diameter of the wire As the aspect ratio decreases the ring will re quire more pressure to weld properly Rings with an aspect ratio of 4 1 or less may be difficult for some people to weld As the aspect ra tio increases or decreases the electrodes should be adjusted outwards or inwards to compensate for the changing angle between the ring and electrodes Cuts Pinch cut rings have the highest resistance at the cut so they start a weld easily but have problems with the ring ends slipping off each other as they melt under pressure This usually results in off round rings and large burrs in the weld The welds are generally strong and with aggressive tumbling are good for armor Shear cut and machine cut rings are of roughly equal quality They weld easily and don t slip often resulting in a more rounded ring Because the ends are more flush they generally have smaller burrs and more consistent welds can be made These types of rings are ideal for most applications Saw cut rings can be a little more difficult to weld since the cut has lower resistance however these rings give the nicest looking welds with little to no burring If you are making jewelry
11. etal can be welded before it has a chance to oxidize This technique is also known as a solid state bond since the metal will not be entirely mol ten when welded Some oxides will form but the pressure of the weld should help to expel them from the weld joint Reactive metals are relatively expensive and when welding them you should expect a higher than normal amount of bad welds Keep this in mind when estimating material costs In many cases it may be less expensive to use inert gas shielding for consistently good welds Aluminum Copper Silver amp Gold In theory any metal can be resistance welded but in practice some are just too difficult without very expensive equipment The metals that are most difficult to weld are silver gold copper and aluminum in that order All of these metals have very low resistances and tend to melt or blow apart when you try to weld them Silver and gold in par ticular should not be resistance welded since they are much more ex pensive and also very easy to solder or braze 15 Types Of Welds Solid Welds Solid welding refers to the technique of setting the heat or weld time lower than normal to create a weld area where there is little to no flow of metal A solid weld is most useful for cosmetic purposes when working with saw cut rings It can be a full strength weld but is more likely to be 60 90 strength which is still many times the strength of a butted ring Precise settings and low pressure
12. ing istance Weld Res of Butted Rings By Eric Matwe 2010 by Eric Matwe All rights reserved No part of this book may be used or reproduced in any manner whatsoever without prior written permission except in the case of brief quotations under the doctrine of fair dealing Published by Lady Lu Computer Support amp Print Shop Riverhurst SK CANADA Cover picture courtesy of TheRingLord com Product Liability Disclaimer Terms of Use Warranty and Liability Waiver TheRingLord com offers this product with the terms conditions and notices as follows Terms of Use This product is offered to you conditional upon your acceptance without modification of the terms conditions and notices contained Exclusive Obligation This product has been designed for the purpose of welding rings This product may not be used for any purpose other than that intended such use is strictly prohibited under the terms and conditions of its use Warranty This product is not manufactured by TheRingLord com and TheRingLord com therefore offers no warranty or implied warranty of fitness for any particular purpose Limitation of Liability In no event shall TheRingLord com be liable for any direct indirect punitive incidental special consequential damages whatsoever arising out of or connected with the use or misuse of this product Other Statements TheRingLord com employees or representatives oral or other written statements do
13. not constitute warranties shall not be relied upon by the buyer and is not part of the contract for sale Entire Obligation This Product Liability Disclaimer document states the entire obligation of TheRingLord com with respect to this product If any part of this disclaimer is determined to be void invalid unenforceable or illegal including but not limited to the warranty disclaimers and liability disclaimers and liability limi tations set forth above then the invalid or unenforceable provision will be deemed superseded by a valid enforceable provision that closely matches the intent of the original provision and the remainder of the agreement will remain in full force and effect General This disclaimer statement is governed by the laws of the province of Saskatchewan Canada You hereby consent to the exclusive jurisdiction and venue of the Courts of competent jurisdiction Canada in all disputes arising out of or relating to the use of this product Use of this product is unauthorized in any jurisdiction that does not give effect to all provisions of these terms and conditions including with out limitation this paragraph Modification of Terms and Conditions TheRingLord com reserves the right to change the terms conditions and notices under which this product is offered Table Of Contents Introduction tennis Welding Precautions eeeens Inchided In this Kit aan Setting Up Your Welder
14. orum is there for you if you have problems using your resistance welding kit or want to share your own tips with other users http www theringlord org forum Index php On the forum you can interact with other users of the resistance welding kit or get help directly from TheRingLord com s profession als As an active member on the website I look forward to meeting you there Eric lorenzo Matwe 20 Shop Notes Shop Notes About the Author Eric Matwe is a professional maille craftsman who spe cializes in welding and automated production techniques He has 5 years experience working at TheRingLord com and 3 years experience repairing maille armor for the meat packing industry Prior to that he was a semi professional maille enthusiast and one of the founding members of the Maille Artisans International League
15. r OEM s user manual that came with your welder Welding Precautions As with any electrical device be aware that electrical shocks can potentially be fatal Don t operate the welder in damp or wet conditions or expose it to water Don t let your body touch a grounding surface while operating the welder Inspect electrical components for damage before using the welder Be aware that the electrodes are live during operation of the welder The electrical currents involved in welding create a strong magnetic field This magnetic field can disrupt electronics and medical devices such as pacemakers Any person who uses such a medical device should consult with their physician before attempt ing to use any welding equipment Resistance welding involves heating metal to near its melting point Too much heat can cause an expulsion of sparks and molten metal droplets Do not operate your welder near anything flamma ble or with children or pets nearby Your welding kit contains a pair of heat resistant gloves to wear while welding You may also want to buy a clear plastic face shield to protect your face and eyes from stray sparks It is best to wear clothing that fits well and covers your arms legs and feet to avoid burns Avoid open toed shoes sandals and low cut necklines Synthetic fibres and terrycloth catch fire easily from sparks do not wear them Included In This Kit 1 115V AC resistance welder transformer 2 Electrode assembly
16. rs ranging from 1 16 to 1 Adjust the electrodes by rotating the adjustable arms they are mounted on If you intend to weld rings outside this range you may need to modify or re place the electrode assembly Timing Circuit To install the timing circuit it should be bolted through the center hole to the welder body Be sure that both the timing circuit and the welder s power source are unplugged before proceeding Disconnect the OEM switch from the wires and crimp the supplied yellow termi nals to the stripped ends of the wires then connect those terminals to the matching relay terminals on the timer For illustration refer to page 6 fig 1 1 and page 7 fig 1 2 Turn the potentiometer knob on the timer to adjust the duration of the weld The duration is adjustable between 0 02 and 2 seconds and is actuated by the foot pedal The expected lifespan of the timer relay is at least 500 000 welds and probably more Optional Variac If you have a Variac you may plug the welding power source into it to allow control of the weld voltage Be sure that you don t set the Variac higher than 115V The welder is designed to handle 115 Volts which is on average what a North American outlet supplies The ac tual voltage supplied in North America can vary widely between 100 130 Volts depending on many factors A Variac enables consistent welds on very small rings Decrease the voltage to decrease the heat of the weld Due to the construction of
17. then these are definitely the rings you want Be aware that due to the gap be tween the ends these rings will become more ovoid than shear cut rings 12 Operator Variables Pressure There are two variables that must be controlled manually by the operator The first variable is pressure As pressure is increased resis tance will decrease The more pressure that is applied between the ring and the electrode the less heat will be generated there and the more heat will be generated directly between the butted ends This helps minimize the heat affected zone and also presses the butted ends together ensuring a good weld It is important to apply consistent pressure to the ring throughout the three phases of the weld cycle Too much pressure will create a large burr or misalignment in the weld Too little pressure will result in brittle welds Electrode Maintenance The second variable is electrode maintenance Keeping the elec trodes clean and undamaged ensures correct alignment of the ring s ends and low resistance between the ring and electrodes Electrodes should be cleaned and repaired by dressing them lightly with a fine toothed triangular file When the electrodes become badly worn or damaged they must be replaced TheRingLord com has replacement electrodes available 13 Commonly Used Metals Iron amp Steel Iron and iron alloys notably the various types of steel are the most commonly welded metals These metals resistance
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