Titanium Casting Troubleshooting Guide
Contents
1. e g Rematitan Ultra Drying time too long or temperature too high Too much moisture retained in the model strong ammonia odour Not adhering to preheat times and temperature Cools too quickly from 1000 C to 430 C e g furnace door open or badly sealed furnace Furnace temperature control faulty Furnace temperature too high when inserting moulds Check vacuum and seals of the vacuum mixer Adhere to mixing time Store the mixing liquid all year round in a refrigerator 12 C 14 C Only use the measuring beaker for Rematitan Plus liquid Fan assisted drying cabinet drying time 40 minutes at 70 C Then dip in Rematitan cold model hardener for 5 seconds Dry the model after dipping for 5 minutes at 70 C Non fan assisted drying cabinet or preheat furnace 40 minutes at 100 C Then dip in Rematitan cold model hardener for 5 seconds Dry the model after dipping for 5 minutes at 100 C Adhere to investment instructions for use Keep the furnace door closed during the cooling phase Cooling from 1000 C to 430 C takes approx 2 5 3 hours Check furnace setting thermocouple control Allow the furnace to cool to room temperature Moulds crack during preheating CrCo moulds crack during casting CrCo moulds crack during casting especially with full plates Incomplete casting ENGLISH Storage temperature of mixing liquid too high Sprue former not p2. high when inserting moulds to room temperature Mixing liquid and powder Use a separate measuring contaminated with other beaker and mixing bowl for investments Rematitan Ultra Moulds too close to the door Position as close as or heated walls in the possible to the centre preheat furnace of the furnace chamber Too many moulds in the Fill furnace to max 2 3 preheat furnace capacity Moulds crack during preheating Incomplete casting ENGLISH Wax patterns too close to the casting ring or not enough investment over the pattern Ring liner not shortened Ring liner too thick Paper ring liner Due to the different types of furnaces cracks can occur despite special batch temperature and heat soak times Faulty furnace temperature control Cracked mould Incorrect pattern thickness Distance between wax pattern and casting ring approx 6 8 mm Distance from the wax pattern to the top of investment approx 8 10 mm Shorten the ring liner Leave a 5 mm area at both ends of the casting ring without ring liner Use a 1 mm thick ring liner mineral ring liner e g Kera ring liner Use a mineral ring liner Calibrate the preheat furnace regularly see page 12 Fan assisted furnaces use the same temperature as that given in the batch instructions Extend the heat soak time gradually by 10 30 minutes Non fan assisted furnaces generally increase the temperature given in the
3. SH Precast functional check Autocast Autocast Plus Rematitan 1 Check that the chamber and copper crucible are clean and free of titanium residue Check the tip of the tungsten electrode If the tip is blunt regrind to an angle of 50 using a tungsten carbide cutter Check the distance to the electrode with a gauge The distance between the tip of the electrode and the titanium ingot should be 5 mm Check the copper crucible Sandblast the oxide layer away completely after 3 castings using Al O grit size 110 125 um Preparing for casting 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 PS Open the argon cylinder and check the level and cylinder pressure Switch to ON Insert the crucible Position the titanium ingot on the crucible Enter the weight of the titanium ingot in the casting machine Press the mould and seal onto the seal of the copper crucible Check that the mould is pressed onto the centre Close the door Press Start The programme is fully automated The programme is complete when both manometer indicators are at 0 Autocast Autocast Plus Open the door remove the mould and quench it with water Remove the crucible and quench it with water Switch to Off Close the argon cylinder Information about the maintenance of your casting machine is included in the instructions for use supplied with the casting machine ENGLISH Precast fu
4. Seal too old poor seal Wax patterns for crowns and bridges positioned too low in the mould Mould cracked Incorrect pattern thickness Molten metal not hot enough Mould not hot enough Tip of electrode blunt Electrode gap incorrect Crucible over oxidized causing a loss of energy Mould cracked resulting in reduced argon pressure and insufficient vacuum Insufficient amount of metal Incorrect sprue position Press the mould and seal onto the centre of the seal on the copper crucible throat Renew the seal The upper edge of the wax pattern should be approx 8 mm 10 mm below the rim of the casting ring See Moulds crack Thickness for crown and bridge patterns 0 5 mm upper CrCo 0 8 1 mm lower CrCo bar 4 3 x 2 3 mm Casting temperature of the mould 430 C Regrind the electrode to an angle of 50 Adjust the electrode gap to 5 mm with a gauge Sandblast the crucible with ALO 110 125 um See Moulds crack Use the correct amount of metal CrCo casting 31g or 36g crowns and bridges up to 6 units 22g more than 6 units 31g 14 units 36g Adhere exactly to the prescribed sprue position see instructions for use Inclusions in the castings Inaccuracies in fit ENGLISH Crucible misshapen due to ageing The molten metal no longer flows through the centre of the copper crucible throat Mould and seal not fitted in the centre of the seal on the co
5. Troubleshooting Guide Titanium Casting ENGLISH Dear Customer Titanium casting is a technique that is now routinely used in many laboratories But when work becomes routine it often results in slight carelessness and errors which cause unnecessary problems This brochure is intended to help you identify and remedy the cause of any problems when casting titanium This troubleshooting guide does not deal with porcelain facings on titanium frameworks A separate brochure on porcelain can be obtained gratis from ESPRIDENT the DENTAURUM subsidiary for porcelain which also supplies Triceram bonding porcelain for titanium Order no 989 676 20 Tips for working with Triceram titanium porcelain ENGLISH Contents Rematitan Plus investment procedure Rematitan Ultra investment procedure Preheat furnace temperature check Precast functional check Autocast Autocast Plus Rematitan casting machines Precast functional check Castmatic Copper crucibles for Dentaurum titanium casting machines page ENGLISH Titanium troubleshooting guide Rematitan Plus investment Bubbles in the investment mix Investment sets too rapidly Surface of the investment model CrCo powdery after drying or Wax patterns do not adhere to the investment model Moulds crack during preheating Insufficient vacuum inadequate mixing or air evacuation Temperature of the liquid too high Measuring beaker used for other liquids
6. Use Lubrofilm wetting agent Inclusions in the Mould is cracked in the area Ensure the moulds are castings of the sprue former when positioned securely removed from the preheat furnace Fan assisted furnaces use the same temperature as that given in the batch instructions Extend the heat soak time gradually by 10 30 minutes Non fan assisted furnaces generally increase the temperature given in the batch instructions by 10 C and gradually extend the heat soak time by 10 30 minutes Generally the preheat temperature of 250 C 90 min and the casting temperature of 430 C 30 min remain the same Heat rate 3 5 C per minute Sprue not positioned See Sprue positioning according to instructions instructions Top of the mould not Cutting back the top of the cut back mould allows gas to escape more easily and increases thermal stability Do not use a trimmer Seal not optimal when Check the seal the mould is pressed against Ensure that the mould the seal of the copper crucible is pressed flat throat Insufficient amount of metal Crowns and bridges up to 6 units 22g more than 6 units 31g 14 units 36g Inclusions in the castings ENGLISH Crucible misshapen due to ageing The molten metal no longer flows through the centre of the copper crucible throat Molten metal not hot enough Tip of electrode blunt Electrode gap incorrect Replace the crucible Regrind the electrod
7. batch instructions by 10 C and gradually increase the heat soak time by 10 30 minutes Calibrate the preheat furnace Check the accuracy of the temperature see page 12 See Moulds crack Pattern thickness 0 5 mm Incomplete casting Inaccuracies in fit Casting surfaces not clean ENGLISH Molten metal not hot enough Mould not hot enough Tip of electrode blunt Electrode gap incorrect Crucible over oxidized causing a loss of energy Inadequate regulation of expansion Moulds too close to the door or heated walls in the preheat furnace Wax not burning out without residue Casting temperature of the mould 430 C Regrind the electrode to an angle of 50 Adjust the electrode gap to 5 mm with a gauge Sandblast the crucible with ALO 110 125 um Increased expansion looser fit Increase the final batch temperature in 10 C stages or extend the heat soak time at the final temperature in 10 minute stages Lower expansion tighter fit Reduce the final batch temperature in 10 C stages or reduce the heat soak time in 10 minute stages Caution If the final temperature or heat soak time is reduced too much the investment may become unstable cracking Position as close as possible to the centre of the furnace chamber Use organic wax which burns out without residue e g Star wax Dentaurum ENGLISH Casting surfaces not clean Wrong wetting agent
8. e to an angle of 50 Adjust the electrode gap to 5 mm with a gauge ENGLISH Preheat furnace temperature check basic requirement for the correct use of Rematitan Ultra investment Rematitan Ultra titanium investment requires very accurate temperature regulation to provide the benefits of its excellent properties A fan assisted preheat furnace heated on four sides such as the Protherm from Dentaurum Order no 096 180 00 is recommended The procedure for checking the actual temperature reached by the preheat furnace is as follows Place a piece of pure silver wire approx 10 mm long goldsmith or silversmith on an old porcelain support tray and insert it in the preheat furnace Set the final temperature to 955 C and heat up the furnace Check the wire after holding the temperature for 30 minutes The wire should not yet be ball shaped Now set the temperature to 965 C and wait another 30 minutes Since the melting point of silver is 961 C the silver should now be ball shaped if the furnace temperature is correct If the silver wire is still in the form of a wire checks should be continued in stages of 10 C with a holding time of 30 minutes The resulting temperature difference on the furnace control should be taken into account in future when setting the final furnace temperature for the investment t A check should be carried out every 6 months as the furnace coils age relatively quickly ENGLI
9. nctional check Castmatic 1 2 3 4 nu 11 12 13 14 15 16a 16b 17a 17b 18 Open the argon cylinder Switch to ON Set the power control to 10 Check both chambers to ensure that they are clean titanium residue on the tip of the electrode Check that the clamp in the upper chamber moves easily Insert the crucible carrier and crucible and ensure the markings are correctly placed Insert the ingot and set the electrode tip gap to 5 mm using a gauge unscrew and tighten the grub screw with an Allen key Enter the melting times 22 g 28 sec 31 g 38 sec 36 g 42 sec Remove the crucible carrier crucible and ingot from the upper chamber again Insert the mould with the seal in position in the lower chamber and raise the lift to grip the mould do not exert too much pressure Check the access from the upper to the lower chamber is the sprue hole in line with the crucible throat Insert the crucible carrier crucible and ingot and close the doors Press Start The casting procedure is automatic The yellow indicator should show 0 75 0 78 and the white indicator plus 0 8 bar If the yellow indicator drops to 0 the mould is not sealed cracks or incorrect programme entered Remedy switch off open the door check the mould press once again close the door turn the dial to zero and re enter the required melting time press Start After flooding bo
10. ositioned in the centre of the casting ring This causes uneven distribution of pressure during casting Investment model too thin Investment too thin around the model Investment too thin over the model Only with Castmatic casting machines argon pressure set too high Insufficient investment over full plate model Sprue positioning incorrect Insufficient amount of metal Store liquids in a refrigerator all year round approx 12 C 14 C Place the sprue former centrally to the model or reposition the sprue and sprue former Model should be 10 715 mm thick at its deepest point if necessary increase the thickness of the model base prior to duplication Minimum thickness of investment around the model should be 10 mm Investment thickness should be approx 30 mm from the residual teeth to the top of the sprue former Set the argon pressure on the cylinder pressure gauge to 0 8 bar Trim back the distal area of the model up to the wax pattern Wax the model upright onto the base atan angle of 30 45 Position sprues correctly see instructions Always use 31g or 36g for casting CrCo frameworks For crowns and bridges up to 6 units 22g more than 6 units 31g 14 units 36g Incomplete casting Inclusions in the castings ENGLISH Mould and seal not properly centred at the copper crucible throat The molten metal flows over the seal This reduces the flow velocity
11. pper crucible throat Molten metal not hot enough Tip of electrode blunt Electrode gap incorrect Crowns fit too tightly at the incisal or occlusal Replace the crucible Press the mould and seal onto the centre Regrind the electrode to an angle of 50 Adjust the electrode gap to 5 mm with a gauge Select a suitable spacer for these areas Vacuum formed foil with spacers are recommended ENGLISH Titanium troubleshooting guide Rematitan Ultra investment Bubbles in the Inadequate mixing under Mix for 120 seconds under investment mix vacuum vacuum Check the vacuum Mixture too grainy Mixing time too short Mix for 120 seconds under vacuum Investment takes too Liquid and powder too Temperature of the long to set longer than cold liquid and powder should 2 hrs be 18 21 C Setting takes longer if the temperature is less than 18 C Mixing liquid and powder Use a separate measuring contaminated with other beaker and mixing bowl for investments Rematitan Ultra Moulds crack during Base former removed from Allow the mould to stand preheating mould too soon 1 2 hrs depending on room temperature before placing in the furnace Metal casting ring not used Use a cylindrical metal casting ring Use a 1 mm thick ring liner Size 9 casting ring used Recommended casting ring sizes 3 and 6 Furnace set for weekend Set furnace for overnight Furnace temperature too Allow the furnace to cool
12. th chambers to zero open the door lower the lift remove the mould and quench it immediately Remove the crucible and quench it immediately If the crucible throat and sprue button are connected do not use force to remove the mould Remove the lower spacer and turn the mould to remove it from the chamber Remove any residual titanium from the crucible and blow dry If the residue in the crucible does not loosen do not try to remove it with an instrument Loosen by lightly tapping the back edge of the titanium residue Remove any titanium still adhering to the crucible with a rubber polisher Further castings and checks as from 4 ENGLISH Copper crucibles for Dentaurum titanium casting machines e Order no 090 110 00 for Rematitan and Rematitan Autocast e Order no 090 010 00 for Castmatic These procedures should be followed to ensure the best results from the crucible c Always use dry clean crucibles for casting t Sandblast oxidised crucibles in the sandblaster with Al O 110 250 um c Always use original Rematitan ingots t Place the ingot on the crucible according to the positioning zones see instructions for use for the casting machine c Place the crucible correctly in the crucible carrier see instructions for use t Adhere to the melting times for the different weights of ingot Casting weight 22g 31g 36g castmatic 28s 38s 42s rematitan 29s 40s 46s autocast 32s 43s 49s Note The condi
13. tion of the electrode and the electrode gap also affect the melting process which in turn affects the thermal stress on the crucible We therefore recommend i checking the electrode gap with a gauge and centring correctly i checking the electrode tip t sandblasting the oxidized electrode Extended melting times result in the crucible overheating and delay c Always remove the crucible immediately after use and quench it in cold water t Do not allow titanium residue to cool on the crucible i Do not throw or hit the crucible t Do not use force to remove titanium residue sticking to the crucible Loosen by lightly tapping the back edge of the titanium residue t Use a rubber polisher to remove any titanium residue adhering to the crucible t Replace worn or cracked crucibles Stand of the Information 10 01 20 01 Aueuler wnunelueg Aq palulid 072 578 686
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