Used Center lathes 400-499mm turning diameter over bed for sale (208)

Condition: used, Year of construction: 1955, Heavy lathe, turning machine, lathe, lead screw lathe, lead screw lathe -Handover: in current condition as viewed -Error: Switching spindle, main spindle continues to rotate in neutral switching position -Manufacturer: Weisser, lead screw lathe type G1 -Turning length: 1660 mm -Turning Ø over bed: 480 mm -Turning Ø without bed: mm -Turning Ø over support: 210 mm -Spindle bore: Ø 45 mm -Spindle speeds: 31.5 - 1400 rpm -Three-jaw chuck: Röhm Ø 250 mm -Accessories: incl. tool holder/tools see photos -Tailstock mount: MK4 -Drive motor: 5.5 kW -Dimensions: 3150/1180/H1300 mm Bwsb Exp Tstzf Rhjksl -Weight: 2800 kg

Condition: new, Year of construction: 2025, Functionality: fully functional, center height: 200 mm, quill stroke: 120 mm, quill diameter: 50 mm, total length: 1,950 mm, total width: 1,060 mm, total height: 1,635 mm, spindle speed (max.): 3,000 rpm, spindle speed (min.): 40 rpm, rotational speed (max.): 3,000 rpm, rotational speed (min.): 40 rpm, three-jaw chuck diameter: 200 mm, Equipment: rotational speed infinitely variable, Whether prototype construction, maintenance or, most importantly, training - EMCO's conventional and cycle-controlled machines manage the balancing act and offer maximum accuracy in the smallest possible space and flexibility down to the last detail. Highlights of the EMCOMAT 20D- Main spindle DIN55029- Tailstock (eccentrically adjustable)- Simple steel holder (clamping claw)- Belt drive for feed gear- Chuck protection with electric limit switch- Optional equipment such as coolant device, sliding chip guard doors etc.Working range:- Travel in X/Y/Z: 220 / - / 1010 mm- Center distance: 1000 mm- Center height: 200 mmMain spindle:- Max. travel distance in X/Y/Z: 220 / - / 1010 mm- Max. travel distance in X/Y/Z: 220 / - / 1010 mm- Max. travel distance in X/Y/Z: 1000 mm Speed: 3000 rpm - Spindle connection: Size 5 (DIN 55029)- Max. speed: 3000 rpm - Spindle connection: Size 5 (DIN 55029)- Max. speed: 3000 rpm - Max. speed: 3000 rpm - Spindle connection: Size 5 (DIN 55029)- Max. speed: 3000 rpm Drive power: 5.3 kW Tailstock:- Inner cone: MK3- quill stroke: 120 mmm- inner cone of the quill: 50 mm Bsb Ejd D I Thoxp Tkjwl

Condition: new, turning length 850 mm turning diameter 400 mm swing diameter over bed slide 245 mm Bweb Expou E U Rae Tksl spindle bore 52.0 mm turning speeds 45 - 1800 U/min bed width 260 mm spindle taper DIN 55029 D 1-5 taper in tailstock 3 MK quill travel 120 mm total power requirement 3.0 / 4.5 kW weight of the machine ca. 1255 kg range L-W-H 1900 x 1000 x 1610 mm Equipment: - 3-axis digital display ES-12 V with LCD display - 3-jaw chuck PS3-200 mm / D5 - Clamping disk 320 mm - Fixed steady rest - passage diameter max. 130 mm - Follow-on steady rest - passage diameter max. 100 mm - Coolant system - Quick-change tool holder with 4 inserts - Protective device for quick-change tool holder - Micrometer longitudinal stop - Slip clutch - Motor with magnetic brake in accordance with CE standard - Initial filling with Shell Tellus 46 - Extendable chip tray - LED machine light - Change gears - Reduction sleeve - 2 centering points - Chip rear wall - Operating tool

Condition: new, Year of construction: 2025, CORMAK 400 metal lathes is a new, improved version of the popular metal processing lathes. Among other things, the tool holder cover, spindle bearing system, new digital readout have been improved. They are suitable for production plants, workshops and tool shops. They are perfect for unit and small lot production. NEW, IMPROVED MODEL !!! high-quality and reinforced spindle bearing system new guards system compliant with CE standards the latest model of digital axis reading reinforced and modernized lathe base with drawers for tools and an extendable chip tray Characteristics of the machine REINFORCED, RIBBED SURFACE OF THE LATHE'S BED PROVIDES MAXIMUM REDUCTION OF VIBRATION, ADDITIONALLY PRECISE GRINDED, HARDENED BED DIGITAL READOUT OF THE AXIS IN STANDARD EQUIPMENT LARGE SPINDLE BORE PROVIDES OPTIMUM PERFORMANCE 52 mm THE APPROPRIATE BED WIDTH ENSURES STABLE AND PRECISE WORKING CONDITIONS MACHINE EQUIPPED WITH HIGH-QUALITY AND HARDENED SPINDLE BEARING SYSTEM EFFICIENT MACHINING THANKS TO TWO AUTOMATIC FEEDS AND EQUIPMENT WITH A ROLLER AND A DRAFT BOLT HARDENED WHEELS IN THE SPINDLE GEAR ADJUSTABLE CLUTCH OVERLOADS ON THE PULL SHAFT POSSIBILITY TO MACHINE THE FULL RANGE OF THREADS WITHOUT REPLACING THE WHEELS IN THE GUITAR FEED CHOICE LOCK: THROUGH SCREW OR SHAFT THE REMOVABLE BRIDGE ENABLES THE WORKING OF ELEMENTS WITH AN INCREASED DIAMETER RETRACTABLE CHIP DRAWER AND TOOL DRAWERS FOR BETTER AND EFFICIENT WORK Technical data Bjb Exp Tjiz Tczokowl MAXIMUM TURNING DIAMETER 400 mm MAXIMUM TURNING DIAMETER OVER THE BED 250 mm MAXIMUM TURNING DIAMETER IN THE SELECTION OF THE BRIDGE 520 mm TURNING LENGTH IN DEAD CENTRES 1000 mm BED WIDTH 218 mm SPINDLE END CAMLOCK D5 SPINDLE CONE MK6 SPINDLE BORE 52 mm SPINDLE ROTATION RANGE 65-1810 rpm SPINDLE SPEED NUMBER 16 ranges RANGE OF LONGITUDINAL FEED (40) 0,053 - 1,291 mm RANGE OF TRANSVERSE FEED (40) 0,011-0,276 mm THE MAXIMUM DIMENSION OF THE TOOL 20 mm x 20 mm METRIC THREAD 0,4-7 mm INCH THREAD 4-60 T.P.I. MODULAR THREAD (22) 0,4-3 mm THREAD D. P. (28) 8-84 D. P. TAILSTOCK QUILL DIAMETER 50 mm TAILSTOCK QUILL STROKE 110 mm TAILSTOCK TAPER MT4 ENGINE POWER 2,2 kW PUMP POWER 0,1 kW WEIGHT 640 kg DIMENSIONS 2000x820x1650 mm EQUIPMENT digital readout steady rest follow rest 200 mm 3-jaw chuck 200 mm 4-jaw chuck face plate 280 mm dead center MK4 x 2 reduction sleeve MK6/MK4 keys Factory new machine, under warranty For more information you can visit our web page.

Year of construction: 1955, Condition: used, serial number 80131-0271 Bobjkxhras Exp Tkjwl centre distance 2000 mm centre height 250 mm bore diameter 63 mm with digital read-out K+C Easson10L voltage 380 V 220 V ampere 16 A

Condition: good (used), Technical data: Bsb Expoqff D Is Tkewl - Center height 220 mm - Turning diameter over bed 440 mm - Center height over bridge 330 mm - Turning diameter in the offset 630 mm - Center height / turning diameter over support 135 / 270 mm - Center distance 1000 mm - Spindle bore 52 mm - Taper of the tailstock quill MK 4 - Travel of the tailstock quill 310 mm - 18 spindle speeds 25 - 2000 rpm - feeds longitudinal + plane - metric thread / Withworth thread / modular thread / DP thread - Drive 400 V / 6 kW - 4-jaw chuck with interchangeable jaws and center point, new Multifix size B with 3 inserts

Condition: used, Lathe, lathe, master and feed spindle lathe, master and feed spindle lathe -Manufacturer: AFM Bebshwt Aie Exp Tkjwl -Turning length: 1200 mm -Swivel O over bed: 460 mm -Swivel O without bed: 620 mm -Rotating O over support: 230 mm -Spindle bore: O 38 mm -Spindle speeds: 22.4 - 1000 rpm -Three-jaw chuck: O 200 mm -Quick change: Multifix steel holder -Tailstock mount: MK4 -Accessories: incl., see photos -Dimensions: 2420/770/H1260 mm -Weight: 1271 kg

Condition: used, machine/vehicle number: 170009, turning diameter over bed:400 mm turning diameter over slide rest:250 mm turning length:1000 mm max swing over gap:520 mm Height of centres:200 mm crossed path:230 mm bed width:218 mm main spindle bore:52 mm spindle size:MK 6 speeds::55-2000 U/min turning angle of tool post:90 grad tail stock:50 mm taper in tailstock:MK 4 threading metric:0,4-7 mm threading WHITWORTH:4-60 TPI total power requirement:2,2 kW dimensions of the machine ca.:1940 x 820 x 1545 mm weight of the machine ca.:750 kg Bsb Exjdmrcrop Tkowl tailstock quill:110 mm tapping modul:0,4-3 mm tapping diametral:8-84 Gang/Zoll

Condition: new, turning length 1000 mm turning diameter 360 mm turning dia. in gap 480 mm spindle bore 51,0 mm turning speeds 70 - 2000 U/min bed width 185 mm spindle taper 55029 D 1-5 taper in tailstock 4 MK quill travel 110 mm total power requirement 1,5 kW weight of the machine ca. 540 kg. range L-W-H 1920 x 750 x 1600 mm Equipment: - 3-axis digital display i200 with LCD display - 3-jaw chuck DK11-200 mm / D5 - Faceplate 200 mm / D5, according to DIN 55029 - Fixed steady rest - passage diameter max. 70 mm - Follow-on steady rest - passage diameter max. 50 mm - Coolant system - Initial filling with Shell Tellus 46 - Extendable chip tray - Clamping disk 320 mm - Quadruple tool holder - Protective device for quadruple tool holder - Slip clutch - Micrometer longitudinal stop - Thread gauge - LED machine light - Reducing sleeve - Change gears - 2 centering points - Foot pedal with brake function according to CE - Motor with magnetic brake according to CE standard - Base frame - Operating tools Bsb Eeu E U Npjxp Tkswl

Condition: new, Year of construction: 2025, One of our best-selling conventional lathes, this lathe can be used for many tasks such as turning internal and external surfaces as well as tapers, polishing, modular and DP threading, drilling and internal broaching. Machine features Lathes from this series can be used for many tasks such as turning internal and external surfaces, tapers turning, buffing, modular and DP threading, drilling and internal broaching By default equipped with a 3 axes digital readout Modern and precise spindle bearings 52 mm large spindle bore Heavy bed made of cast iron, ground and inductively hardened Gear wheels strengthened through hardening and precise grinding Removable bridge allows for greater machining capabilities Protection guards compliant with the newest regulations Machining accuracy: circularity deviation below 0.01 mm, cylindricality deviation no more than 0.02 mm for 200 mm long measurement, perfect surface finish Equipped with a mechanical foot mechanical brake Possibility of equipping the lathe with a ruler for turning tapers Optional VARIO model with a smooth spindle speed adjustment and a digital indicator Technical data Swing over bed 410 mm Swing over cross slide 255 mm Swing over gap bridge 580 mm Turning length in gap bridge 190 mm Centres distance 1000 mm Centres height 205 mm Bed inductively hardened Bed width 250 mm Spindle bore diameter 52 mm Spindle tip D1-6 Spindle mount MK6 Spindle speed (16) 45–1800 rpm Maximum tool dimensions 20 mm×20 mm Longitudinal feed range (17) 0.05–1.7 mm/turn Transverse feed range (17) 0.025 – 0.85 mm/turn Metric thread (42) 0.2–14 mm Inch thread (45) 2–72 T.P.I. Modular thread 0.3–3.5 M.P (18) D.P. thread 8–44 D.P. (21) Tailstock quill diameter 50 mm Tailstock quill extension 120 mm Tailstock quill tip MK 4 Digital readout in 3 axes Main motor power (S1/S6) 2.2/3.3 kW Flood coolant pump power 0.1 kW Dimensions 1940×850×1320 mm Weight 1590 kg Default equipment 200 mm 3-jaw lathe chuck 250 mm 4-jaw lathe chuck 3 axes digital readout Face plate Steady rest Follow rest Spindle reducing sleeve Dead centre Change gears for the swing-frame of the gear train Cooling system Lighting installation Thread indicator (gauge) Lathe equipped with an electromechanical foot brake compliant with EC regulations Chips container Set of handling tools Protective guards compliant with the newest EC regulation User manual EC declaration of conformity Factory new machine under full warranty Factory new machine, under warranty For more information you can visit our web page. Bjb Eeiz Tf Sjxp Tkowl

Condition: used, L + Z Lathe WEWAG Model 250 / 1500 make no. 20953 year of construction approx. 1975 Bsb Exslzm Eqep Tkewl center distance 1500 mm nominal turning diameter over bed Ø 500 mm turning diameter over bed max. Ø 510 mm Center height over bed 255 mm turning diameter over support Ø 300 mm Center height over support 150 mm spindle bore Ø 56 mm Spindle speed 18 - 1800 rpm. 24 steps lathe chuck support short taper DIN 55022 tailstock inner taper MK 5 drive power 4 kW and 6,7 kW pole-changing - 3-jaw lathe chuck BISON, Ø 250 mm - steel holder 4-fold for turning - fixed lynette - control cabinet fixed on the back of the machine weight 2500 kg

Condition: repair required (used), turning diameter over bed 400 mm turning diameter over slide rest - mm turning length 1000 mm Bwjb Exeu Tkqiop Tksl total power requirement 9 kW weight of the machine ca. 2 t dimensions of the machine ca. 2,5*1,2*1,6 m Machine has been partially overhauled Among other things engine renewed ( 8.000 EUR ) The repair was not completed due to plant closure

Condition: good (used), Year of construction: 1992, machine/vehicle number: 144150920187, Offer 24009 Technical data: - Center height 200 mm - Center width 1500 mm - Largest circulation - Ø over bed 400 mm - over cross slide 210 mm - spindle bore 56 mm - Taper of the tailstock quill MK 5 - Travel of the tailstock quill 150 mm - Spindle speeds 11 - 2240 rpm - feeds longitudinal + plane - Metric thread pitches Bjb Exorvx Najp Tkewl - inch thread - modular thread - Diametral pitch thread - Drive 400 V / 7.5 kW - 3 jaw chucks - Space requirement approx. W 3300 x H 1600 x D 1200 mm - Weight approx. 2800 kg

Condition: new, TC 205 x 1000 Center height: 205 mm Swing diameter over bed: 410 mm center width: 1000 mm bed width: 260 mm spindle nose: DIN 55029 (Camlock) 9, size 6 traverse path cross slide: 220 mm travel top slide: 125 mm spindle bore: 52,5 mm Spindle speeds: 20 - 3000 min-1 Speed control: Stepless Mechanical preload stages: 2 motor power: 3,75 kW coolant pump: 0,13 kW longitudinal feeds Z: 0,05 - 1,7 mm/rev face feeds X: 0,025 - 0,85 mm/rev Whitworth threads: (45) 2 - 72 TPI Metric threads: (39) 0.2 - 14.0 mm Diametrical threads: (21) 8 - 44 DP Module thread: (18) 0.3 - 3.5 MP Quill diameter: 52 mm Internal taper quill: MK 4 quill stroke: 150 mm dimensions: 2270 x 1120 x 1900 mm Weight, approx.: 1500 kg Features: - Machine tool accuracy according to DIN 8605 - Infinitely variable speed control ( 2 preload stages ) - Fine balanced main spindle - Stable machine bed with hardened and ground guides - Monolithic cast iron base - Adjustable precision taper roller bearings in the main spindle - Easy-to-operate feed gear with large feed range running in closed oil bath. - Low maintenance central lubrication - Removable bridge Scope of delivery: - 3-axis digital display (resolution 0.005 mm) - 3-jaw lathe chuck - Quick-change tool holder with four cassettes - High splash guard rear wall and integrated LED tray light - Chip tray can be pulled out to the front - Slipping clutch - Fixed steady rest with ball bearing inserts - Travelling steady rest Bobeir If Do Exp Tkewl - Micrometer bed stop - Machine shoes (1 set of 6) - Two emergency stop buttons - Foot pedal with double braking device ( mechanical and electrical ) - Limit switch secured chuck protection, rotating steel holder protection and cover of the leading and traction spindle according to the European safety standards CE - Coolant device - 2 fixed center punches - Reducing sleeve for main spindle - Operating tool - Operating tool in tool box - Operating manual with spare parts list

Condition: new, turning length 1500 mm turning diameter 420 mm swing diameter over bed slide 255 mm turning dia. in gap 580 mm spindle bore 52.0 mm turning speeds 45 - 1800 U/min Bob Expju Elpms Tkewl bed width 250 mm spindle taper DIN 55029 D 1-6 taper in tailstock 4 MK quill travel 140 mm total power requirement 3.0 / 4.5 kW weight of the machine ca. 1400 kg range L-W-H 2570 x 900 x 1600 mm Equipment: - 3-axis digital display ES-12 V with LCD display - 3-jaw chuck DK11-200 mm / D6 - Clamping disk 350 mm - Fixed steady rest - passage diameter max. 135 mm - Follow-on steady rest - passage diameter max. 65 mm - Coolant system - Quadruple tool holder - Protective device for quadruple tool holder - Micrometer longitudinal stop - Slip clutch - Turret stop with fine adjustment - Thread gauge - Motor with magnetic brake according to CE standard - Foot pedal with brake function according to CE - Initial filling with Shell Tellus 46 - LED machine light - Change gears - Reduction sleeve - 2 centering points - Chip back wall - Operating tools - Operating instructions

Condition: used, turning diameter over bed 380 mm turning diameter over slide rest 200 mm Bweb Exevn U Nkop Tksl turning length 1100 mm turning diameter in the gap mm turning speeds 375 - 1050 U/min centre height 190 mm spindle bore 50 mm total power requirement 4,0 KW weight of the machine ca. 1,8 t dimensions of the machine ca. 2,5 x 1,3 x 1,5 m Lead and spindle lathe - 3-jaw chuck 200mm - 4-way tool holder - Chip tray - Keyless drill chuck

Condition: good (used), Year of construction: 1974, Type / model: 16K20 Control: conventional Center distance: 750 mm Passage: 55 mm Bweb Expsvug Dte Tkjl Center height: 220 mm Turning diameter over bed: 440 mm Speed range: 12 to 1,600 rpm Feed: Connection: 10 kW Accessories/equipment: Condition: good Weight: approx. 2.4 t Dimensions: 2,600 x 1,200 x 1,700 mm

Condition: used, Year of construction: 1989, turning diameter over bed 400 mm turning diameter over slide rest - mm turning length 1000 mm total power requirement 9 kW weight of the machine ca. 2 t Bwob Eou Nmzlexp Tkol dimensions of the machine ca. 2,5*1*1,6 m

Condition: excellent (used), Swing over bed 400 mm Distance between centers 1250 mm Spindle speeds 0-2500 rpm Bwjb Exsq Dll Dep Tkel Misc. accessories MARCELS MASCHINEN CH

Condition: new, Precision Center Lathe and Center Lathe Make: OPTIMUM Model: OPTiturn TZ 4V Item No.: 3432245 Condition: New machine center height: 200 mm center width: 800 mm speed: 50 - 3.000 rpm infinitely variable via 2 gear steps with SIEMENS Inverter-Vario-drive equipped as standard with: Beb Exog Hkmrop Tkjwl - 3-axis digital display DPA 32 - digital speed display in headstock - fixed center point MK 3 - quick change tool holder size B - turning toolholder BD - reducing sleeve MK 6 / MK 3 - steady rest fixed ø 10 - 130 mm - steady rest travelling ø 10 - 100 mm - Coolant device - Chip tray, extendable - LED machine light - Operating tool

Condition: new, turning length 1500 mm turning diameter 410 mm swing diameter over bed slide 255 mm turning dia. in gap 580 mm spindle bore 52,0 mm turning speeds 30 - 3000 U/min bed width 250 mm spindle taper 55029 D 1-6 taper in tailstock 4 MK quill travel 120 mm total power requirement 5,5 kW weight of the machine ca. 1400 kg. range L-W-H 2530 x 1000 x 1450 mm Bobeu Elmxs Exp Tkowl Scope of delivery - 3-axis digital display ES-12 V with LCD display - 3-jaw steel chuck PO3-200 mm / D6 - Clamping disk 350 mm - Fixed steady rest - passage diameter max. 135 mm - Follow-on steady rest - passage diameter max. 65 mm - Foot pedal with brake function according to CE - Quadruple tool holder - Protective device for quadruple tool holder - Micrometer longitudinal stop - Turret stop with fine adjustment - Frequency converter - Initial filling with Shell Tellus 46 - Coolant system - Slip clutch - Thread gauge - LED machine light - Change gears - Reducing sleeve - 2 centering points - Chip back wall - Operating tool * Images show identical machine

Condition: new, Precision center lathe and feed spindle lathe Make: OPTiturn Model: TM 4010 D Item no.: 3403045 Condition: New machine Center height: 200 mm Boboilup Ne Exp Tkjwl Center width: 1.000 mm Spindle speed: 70 - 2,000 rpm (8 steps) Equipped as standard with - 3-axis digital readout DPA 31 PLUS - Machine base - 200 mm three-jaw chuck - LED machine light - Reducing sleeve MK 4/MK 6 - Fixed center point MK 4 - Steady rest, fixed - Steady rest, moving - Quick-change steel holder Basic body E - Torsion steel holder ED - Chuck protection cover, electrically fused - Oil filling - Operating tool - Operating instructions

Condition: new, turning length 1000 mm turning diameter 380 mm turning dia. in gap 490 mm Bweb Eju Ellboxp Tkol spindle bore 51,0 mm turning speeds 70 - 2000 U/min bed width 185 mm spindle taper 55029 D 1-5 taper in tailstock 4 MK quill travel 120 mm total power requirement 1,5 / 2,2 kW weight of the machine ca. 575 kg. range L-W-H 1920 x 800 x 1660 mm Equipment: - 3-axis digital display i200 with LCD display - 3-jaw chuck DK11-200 mm / D5 - Faceplate 200 mm / D5, according to DIN 55029 - Fixed steady rest - passage diameter max. 70 mm - Follow-on steady rest - passage diameter max. 50 mm - Coolant system - Initial filling with Shell Tellus 46 - Extendable chip tray - Clamping disc 320 mm - Quadruple tool holder - Protective device for quadruple tool holder - Slip clutch - Micrometer longitudinal stop - Thread gauge - LED machine light - Reducing sleeve - Change gears - 2 centering points - Foot pedal with brake function according to CE - Motor with magnetic brake according to CE standard - Base frame with drawers - Operating tools

Condition: new, Year of construction: 2021, Precision center lathe and feed spindle lathe Make: OPTIMUM Model: OPTiturn TZ 4 Item no.: 3432240 Condition: New machine Center height: 200 mm Center width: 800 mm Speed: 45 - 1,800 rpm (16 steps) equipped as standard with - 3-axis digital readout DPA 32 - MK 3 fixed center point - quick-change toolholder size B - BD turning tool holder - Reducing sleeve MK 6 / MK 3 - Fixed steady rest ø 10 - 130 mm - Moving steady rest ø 10 - 100 mm - Coolant device - Chip tray, extendable Bwsb Exp Tsgqw U Rjksl - LED machine lamp - Operating tool

Condition: new, turning length 1000 mm turning diameter 420 mm swing diameter over bed slide 255 mm turning dia. in gap 580 mm spindle bore 52.0 mm turning speeds 45 - 1800 U/min bed width 250 mm Bob Exp Teu Eli Hekswl spindle taper DIN 55029 D 1-6 taper in tailstock 4 MK quill travel 140 mm total power requirement 3.0 / 4.5 kW weight of the machine ca. 1220 kg range L-W-H 2070 x 900 x 1600 mm Equipment: - 3-axis digital display ES-12 V with LCD display - 3-jaw chuck DK11-200 mm / D6 - Clamping disk 350 mm - Fixed steady rest - passage diameter max. 135 mm - Follow-on steady rest - passage diameter max. 65 mm - Coolant system - Quadruple tool holder - Protective device for quadruple tool holder - Micrometer longitudinal stop - Slip clutch - Turret stop with fine adjustment - Thread gauge - Motor with magnetic brake according to CE standard - Foot pedal with brake function according to CE - Initial filling with Shell Tellus 46 - LED machine light - Change gears - Reduction sleeve - 2 centering points - Chip back wall - Operating tools - Operating instructions