Tool and Die Design PTB 31304 Raja Aziz Raja Ma’arof Institute of Product Design and Manufacturing UniKL IPROM
References § Suchy Suchy,, I., Handbook of die design; design; McGraw Hill 2nd Ed., § § § § §
2006. Boljanovic,, V., Sheet Metal Forming Processes and Die Boljanovic Design,, Alkem Design Alkem,, 2004. Alvarez, W., Roll Form Tool Design: Fundamentals, Fundamentals, Alkem,, 2006. Alkem Szumera,, J., The Metal Stamping Process, Szumera Process, Alkem Alkem,, 2003. Spitler,, David (tech. reviewer), Spitler reviewer), Fundamentals of tool design,, Society of Mechanical Engineers, 2003. design Paquin,, J. R., Die design fundamentals, Paquin fundamentals, Industrial Press, 1986
Credit hours § Four (4) credit hours (2K, 2P) § Lecture (room nr 2038) § Two credit hours § Two hours per week § Every Tuesday, 0830 – 1030 hrs
§ Practical (room nr 0016) § Two credit hours § Four hours per week § Wednesday, 0830 – 1230 hrs
§ § § § § § § § §
Main topics Sheet metal die design principles Press machine specifications Die plates and insert materials Detail single die design Detail design for progressive dies, incorporating piercing, blanking, bending, forming, embossing, etc. Deep Drawing Dies Casting Dies Basic operation and design knowledge of specialized dies Large and Super Large Stamping Dies
Sheetmetal Die Making flow Sheet metal product & Product design Ordered volume Volume per batch
Forming machine Forming machine selection Sheet metal die design…
Assessment § Coursework, 60% § At least two assignments: total 40% § At least one on sketching (at 10%) § At least one on Die design using CAD system (SolidWorks / Catia / Inventor) (at 30%)
§ At least one test (mid semester): 20% § Approx 30% on theory § Approx 70% on practical using CAD system
§ Final exam, 40% § Approx 30% on theory § Approx 70% on practical using CAD system
Product design Flat Blank design
Sheetmetal Die Design…
Strip layout design Die design
Machining Assembly Trial and debugging (trouble shooting)
Die commissioning
Sheet metal product design § Dimensioning tolerances § Positioning tolerances § Burr direction § Tensile strength (δ (δ or Rm) (supplier) § Material content (supplier) § Thickness § Surface pressure... Burr:
Flat blank / blank sheet design § Def: Unfolded representation of sheetmetal product design. § It incorporated the forming processes, eg eg.. Bending, deep drawing, embossing, lancing, etc.
§ Cutting clearance § Normally 2 to 5% of strip thickness per side § Die clearance: total clearance (both sides) § Less than 1% per side: to use fine blanking technology 26 July 2011
§ Bending factor / processes § Drawing factor / processes
Blank design with bending § Bending factor (v) parameters § Bending radius (r) § Sheetmetal thickness (t or s)
§ L = a + b + c + ……- n.v § § § §
L = flat blank length a, b, c = flange length (outer side) n = number of bendings v = bending factor
Bending operation: minimum allowable internal radius (r)
Bending operation: determining Bending Factor (v) value
Bending angle: other shapes §
ß = 0º to 90º
§
ß = >90º to 165º
Verhaeltnis r:s = Ratio of radius:thickness
L=a+b–v v = Equivalent Value k = Correction Factor S = Material Thickness
Springback by bending § r1 = kR . (r2 + 0.5.s) – 0.5.s § § § §
r1 = bending radius on tooling r2 = bending radius on product kR = springback factor s = sheet thickness
§ α1 = α2 / kR § α1 = bending angle on tooling § α2 = bending angle on product / workpiece
Springback by bending
Deep drawing (Tiefziehen (Tiefziehen)) § Deep drawing process and components: § § § §
Flat blank sheetmetal Drawing punch Drawing insert Drawing thrust plate
§ Flat blank calculation § Refer to die catalogue #2 § To be discussed in later
Piercing punch stroke § Punch stroke = x + t + y §x= §t= §y= x t y
Punch & Die dimensions
Dpunch
§ Piercing / punching § Dpunch = hole dimension on product
§ Blanking § Ddie = blank dimension on product
Ddie
Cutting & Die clearances § Cutting clearance (Shneidspalt (Shneidspalt), ), U § Per side § U = Ddie - Dpunch 2
§ Die clearance, 2U
U
U
§ Both sides
§ Punch (Schneidstempel (Schneidstempel)) § Die (Schneidplatten (Schneidplatten)) § Hole (Lochen (Lochen)) § Blanking (Ausscheiden (Ausscheiden))
Draft (Free) angle (Freiwinkel)
Cutting angle on Die § Cutting Clearance § § § §
(Schneidspalt Schneidspalt)) Material (Werkstoff (Werkstoff)) Sheet thickness (Blechdicke Blechdicke)) Mit Freiwinkel (with Flat cutting surface cutting angle) Ohne Freiwinkel (Flate cutting surface)
U
Cutting Clearance (U) Based on: 1. Strip thickness 2. Cutting angle on Die 3. Strip Tensile Strength
14 Feb 12
Strip layout design § Production volume (yearly, monthly) § Type § § § §
Single Compound Transfer Progressive (normally Production Vol > 10k / month)
§ Burr direction
Strip layout design (2) § Strip flow § Scrap flow § Product flow § Force calculation § § § § § §
Cutting Stripping Spring Bending Drawing Force centre point
Cutting force (F (Fcut) § Tensile strength (δ (δ or Rm) [N/mm2] § Shear Stress (t (t) = 0.7 to 0.9 δ § Fcut = t [N/mm2] x Acut [mm2] § Fcut = t [N/mm2] x Lcut [mm] x tcut [mm] § Where: § Acut = Cutting cross sectional area § Lcut = Cutting length § tcut = Material thickness
Stripping force § Function: § To strip punches from strip layout
§ The smaller the cutting clearance, the higher the stripping force required § Also it depends on strip material and thickness § Fstrip = 0.2 to 0.5 (Stripping Factor, SFac) of cutting force § SOP for piercing or blanking process § Thrust plate touches and holds strip layout § Then piercing or blanking punch cuts through the strip layout
§ Thus, at opening position, punch must be securely positioned inside the thrust plate
Spring § Types § Elastomer / urethane (normally for stripper spring) § Coil (round & rectangular cross sectional type) § Leaf 21 feb 2012
Strip layout design (3) § Pitch puncher / Notching punch § Function: To ensure strip layout moves forward at a fixed distance § No autoauto-feeder machine § ‘U’ profile; material overcut to avoid obstruction of strip flow § Based on material thickness
§ Pitch / strip stopper § Function: to ensure strip layout stops at the desired position § Fixed on guide fence or die plate (more precise) § Web width
Web design § Minimum web width is required: § To have a stable strip layout § During forward motion § Avoid sagging § To have sufficient thrust force to hold the strip § Insufficient thrust, the strip will be pulled by the punch, hence damaging the strip
Bridge / Web width (W (Wweb)
§ Based on material thickness § Minimum width
§ To reduce scrap. Optimise material utilization, ηMatlUtil (flat blank area / pitch area)
§ Optimum width
§ To have sufficient thrust force to hold the strip. Insufficient thrust, the strip will be pulled by the punch, hence damaging the strip § To avoid incomplete blank / punch operation § To avoid deformation on web, hence strip pitch distance will be distorted § To minimise strip overhang
Streifenbreite = Strip width
§ a = Web width at external profile § b = Web width between profiles
Web design
Strip layout design (4) § Bullet Casing, Mini Stapler § One One--side carrier (bridge / web) § Consider also: § Burr direction § Strip flow (on die or with springspring-activated guide lifter) § Strip over hang condition
Strip layout design (5) § Hinge, Door Bracket § Centre carrier § Take note on three (3) idle stations
Strip layout design (6) § Cap § Two Two--side carrier
Mon 31 Jan 2011
Strip layout design (7) § Opening and closed conditions § Punches and dies § Displacement (closed to open positions)
§ Punch and blank processes § From top preferred § Scrap downwards
§ Strip level position during forward direction § On die plate preferred. No over hang. No guide lifter. Bend down on product parallel to flow (slot on die plate) § At a distance above die plate (with strip lifters) § For product with bends. § For drawing process
Strip layout design (8) § Force calculation § Cutting (pierce, blank, etc.), bending, drawing § Spring § Stripping § Drawing § Return (bending, levelling) § Strip carrier
Stripper spring design
Gap
Stripper spring calculation § FTotalCut=? § FStrip =? § Punch travel distance (x + t + y) § Spring load, Fmax and Maximum deflection fmax per spring? § Nr of spring? § Fstrip strip/spring /spring
Piercing punch stroke § § § §
Punch stroke = x + t + y x = Distance inside trust plate t = Strip thickness y = Punch penetration distance from strip bottom
x t y
Citation & References
§ In text: Based on 90º bending formula, L = a + b + c +… -nv (Heinzler et al., 1997), the flat length is thus xx mm…. (p. 260). § In text: Heinzler et al. (1997) proposes the 90º bending formula, L = a + b + c +… -nv (p. 260). § In references: Heiznler Heiznler,, M., Kilgus Kilgus,, R., Näher,, F., Paetzold Näher Paetzold,, H., Röher Röher,, W., Schilling, K. (1997). Tabellenbuch Metall Metall.. Leinfelden--Echterdingen Leinfelden Echterdingen,, Germany: Europa--Lehrmittel Europa Lehrmittel..
Die design § Standard plates § Top, pressure, punch holder, stripper, thrust § Bottom, die, guide fence
German design
Die design
Japanese design
Die design (Japanese typical design) § Paper stapler, spring puncher § Note: stoppers on top & bottom dies are crucial to avoid over travel of bending and drawing punches
Die design (German typical design)
§ Paper Puncher: Base
Die design § Datum (normally die top position) § Closed position § § § §
Piercing / blanking punches Bending punches Drawing punches Spring maximum load condition
0 Die plate
Die design § Opening position § Spring prepre-load condition. Better life span § Spring selection § Elastomer / urethane spring § Higher force (approx. 20 times higher than coil spring: 150kN) § Lower compressible length (approx. 20%)
§ Coil spring § Higher compressible length (up to 50%) § Max. load approx. 7kN
§ Gas spring § Linear load increase (300N to 180kN) § Drawing and deep drawing process
§ Disc spring
Die design – Spring selection § Lpre pre--Comp, PrePre-load length: 2mm or 5% – 10% of spring length. Higher length for higher compression § Lstroke, Punch stroke = X + T + Y § LDeflTotal compressed length (Deflection) § Consider punches (pierce, bend, draw, etc.) movement
§ Load to strip the strip layout § Spring load at prepre-load length + piercing punch travel up to thrust plate bottom level = F strip
Die design – Spring selection § Assume material: St 7070-2, 3mm thick, total § § § § §
cutting length at 300mm Tensile strength, δ or Rm for St 7070-2 = 690 - 830 N/mm2. assume average, δave = (690 + 830)/ 2 = 760 N/mm2 Shear stress, t = 0.7 to 0.9 δ. Assume average, tave = 0.8 x 760 N/mm2 = 600 N/mm2 F shear or cut = ? N F strip = ? N
Die design – Spring selection § F shear or cut = t x Area cut = t x Lcut x thick = 600 N/mm2 x 300mm x 3mm = 540,000N = 54,000kgf =54T § F strip = 20% - 50% of F cut . Assume Fstrip = 35% of 54T = 19T § E.g. PrePre-load distance = 2mm (Lpt (Lpt), ), pierce punch distance to thrust bottom level distance is 3 (x) and working stroke is 9mm (t + y) § Total spring compressed length = Lpt+x+t+y
Die design – Coil spring selection (Stripper Spring) § Compressed length, f = LPre Pre--Comp + LStroke § LPre Pre--Comp = PrePre-compressed length § fmax (Spring Tech Spec) > f
§ Compressed length, fmax = 2+3+3+6 = 14mm § Consider to use 20 springs § Thus, F strip/spring 19T/20= 0.95T = 9,500N § Select coil spring SB x dia50x70L § 9,807N at 14mm compressed
Die design – Elastomer spring selection § Or 4 springs § Thus, F strip/spring 19T/4= 4.75T = 47,500N § Find spring fmax at 14mm, nearest Fmax at 30,100N for elastomer spring 246.5.090.040 § Nr of springs is 190,000N / 30,100N = 6 springs
Die design – Strip lifter spring § Strip weight = ρ x Volume § Number of springs § Weight per spring to hold strip § Spring selection § Compressed Length f = Lpc + Lstroke § Lpc = PrePre-compressed length § Lc = Ldefl = Lpc + Lstroke
§ fmax (Spring Tech spec) > f
Die design § Punches safety level § Opening and closed positions § Piercing / blanking punches § Bending punches § Drawing punches § Punch stroke § Die total stroke
Die type determination
§ Die life § § § §
Small life volume (<50k): Single die High life volume: Progressive die E/E: product life of 200k to 300k in two years Automotive: product life of 500k to 2mil in five to seven years
§ Case study § Die life of 500k in six years § Monthly volume required: 500k / 6yrs / 12mths = approx. 6,945 monthly
§ Production data § Eight hours per shift § 22 days per month
Production planning calculation
§ Production allocation (Volume per batch)
§ Press machine 80 SPM (eg (eg AMADA TPTP-45 EX) § Press machine cycle time = 1/80 min x 60 sec/min = 0.75 sec § Daily time: 1day x 8hrs per day x 60 min/hr = 480 min / day § Volume / day = 480 min/day x 80 strokes/min = 38,400 strokes / day. § For 6,945 volume per month requirement § Time allocation to produce the part: 6,945/38,400 x 8 hours / day = approx. 1.5 hours
Mon 7 Feb 2011
Production planning calculation: Alternative § Machine cycle time: 0.75 sec § For 6,945 volume, time to produce = 6,945 x 0.75 sec = 5,209 sec § Or 5,209 sec / 3600 sec/hr = approx 1.5 hours
Production planning calculation
§ Production allocation (Volume per batch)
§ Press machine cycle time: 60 to 100 spm. Take average, 80 spm § Take average to cater down time & maintenance § Cycle time or time per stroke or time per piece § Cycle time = 1/80 spm or 0.0125 min/stroke or 0.75sec (60sec/80spm) § Daily volume: 8hrs per day x 3,600sec per hr / 0.75sec per stroke = 38,400 strokes per day (press machine capacity). § For 6,945 volume per month requirement § Nr. of days allocation per month: 6,945 units/38,400 units per day = approx. 0.2 day, namely 0.2day x 8hrs per day= 1.6hrs for one shift to produce one month requirement (6,945 units)
Forming / Stamping machines
C-Frame Hydraulic press
Stamping / forming machine § Machine tonnage § Bolster size § Slide size § Shut height § Stroke § Die height (closed position)
Tue 20 Sept 2011
Stamping machine selection § Tonnage § Cutting, bending, drawing, stripping forces
§ Opening height § Stroke § Tightening position § Bolster dimension § Slide dimension
§ Feeding method § Die height § Die weight
Bending force parameter calculations § V-Bending Rm = Tensile Strength Fb = C x Rm x b x S02
Fb1 = 2 x Fb S0 b
W r C = 1 + 4S0 W
W C = Bending factor Fb = Open bending Fb1 = Closed bending
Bending force parameter calculations Fb
§ U-Bending S0
Uniform bending
b1
b2
Fb = 0.4 x Rm x b x S0 L- Bending (one side)
L
Fb = 0.2 x Rm x b x S0
Non-uniform bending Fb = 0.2 x Rm (b1+b2) x S0 Bending without opposing spring Ff = 2.5 x Fb Mon 12 Oct 09
Ff
Bending force parameter calculations § U-Bending
Fos
Bending with opposing spring Fos = 1.3 x Fb
Opposing spring
Deep drawing: flat blank § Tiefziehen = Deep drawing § Ziehtail = Drawn component § Zuschnittdurchmesser = Diameter of flat blank § Ohne Rand = without additional flat ends (lips) § Mit Rand = with additional flat end
Deep drawing: Flat blank calculation
Deep drawing: Drawing clearance & corner radii § Ziehspalt und Radien am Ziehring und Ziehstempel = Drawing clearance & drawing radius on drawing ring & drawing punch
w
Drawing Clearance
s
Sheet Thickness
k
Sheet Material Factor (Wekstofffaktor)
rr
Corner Radius at Drawing Ring
rp or rst
Corner Radius at Drawing Punch
D
Cut Sheet Diameter
dr
Drawing Ring Diameter
d
Punch Diameter
Stahl = steel Sonstige NE-Metalle = Special non-ferrous metal
Deep drawing: Drawing clearance & corner radii
Deep drawing parameter: Number of drawing stages and drawing factor § Ziehstufen &
§ § § §
Ziehverhaeltnis = Number of drawing stages and drawing factor Werkstoff = Material Zwichengluehen = heating during drawing Mit = with Ohne = without
§ Zug = Travel D
Cut Sheet Diameter
d1
First Stage Punch Diameter
d2
Second Stage Punch Diameter
b1
First Stage Drawing Factor
b2
Second Stage Drawing Factor
s
Sheet Thickness
Deep drawing parameter: Number of drawing stages and drawing factor
Deep drawing parameter: Number of drawing stages
Deep drawing: force calculations § Force calculation § Tiefziehkraft = Deep
FD or Fz
Deep Drawing Force
d1
Punch Diameter, first stage
s
Sheet Thickness
drawing force § Niederhalterkraft = Thrust plate force
Rm
Tensile Strength (or δ)
b
Actual Drawing Factor
bmax
Highest Allowable Drawing Factor
FT or FN
Thrust or Holding Force
D
Cut Sheet Diameter / Flat blank diameter
dN
Diameter on holding plate
p
Thrust Plate Pressure
w
Drawing Clearance (per side)
Deep drawing: force calculations
Dimensioning & machining procedures
§ Standard: ±0.1 § Standard : ±0.05 (pressure and punch holder) § Thrust plate § Vertical: 0 to +0.05 § Horizontal: ±0.1
§ Guide fence § Horizontal top: -2 to - 3 § Horizontal bottom: -0.1 to -0.2 § Vertical: 0 to -0.05 In mm
Dimensioning § Die plate assembled in ground plate § Vertical: 0 to +0.1 § Horizontal: -0.1 to 0
§ Die plate opening, on top of ground plate § Horizontal: +0.1 to +0.2 § Vertical: ±0.05
Die materials
§ Base plates: Mild steel. E.g. MS45, C45 § Punches § Materials: HSS (Euro), DF2, SKD11, SKH § Hardness: HRC 60 - 64
§ Inserts § Materials: HSS, DF2, SKD11, SKH § Hardness: HRC 55 – 63 (normally lower than punches for maintenance purpose. Insert to break rather than punch)
§ Standard parts § Guide pillars & bushes (SUJ2,…) § bolts
Common problems in sheetmetal products
§ Burr § Higher than specification § Wrong direction
§ § § § § § § §
Dented: Foreign materials Different thickness / surface thinning Elongated hole (bend after hole punch) Wrinkle surface Torn off Springback Surface crack Rusty
Finished product problems in sheetmetal
Wrinkle
Surface thinning
Common problems on sheetmetal die
§ Misalignment between top and bottom die plate sets § Forming machine stops halfway through § Insufficient load § Obstruction between punches and dies
Tue 18 Oct 2011
Special sheetmetal dies § Cam design, angular cut / bend § Side cut § Sensors § Air Air--assisted scrap / product removal
Special forming machines § Fineblanking § Highspeed forming machines § Multi Multi--actions bending machines § Sensors in forming machines
Cost calculation: Main cost components
§ Design § Raw materials and standard parts § Machining § Heat treatment § Handling § Delivery § Administration § Profit margin § Quotation
Design cost § RM / hr § Design duration § Design objective (based on problem statement) § Design needs analysis § Research ideas § Design alternatives § Final design
Raw material & standard part cost § Raw material, by: § Request for quotation from suppliers § Weight § Size or volume
§ Standard part catalogue § Price list from suppliers § Request for quotation from suppliers
Machining cost § Machine type § § § § § §
Milling Turning Grinding Wirecut Diesink Welding
§ Machining accuracy § Machining time calculation § RM / hr rate, by machine depreciation
Machining cost
§ Normally based on depreciation § Cost to purchase a machine, e.g. RM300k (plus § § § § § § § §
interest) For forming machine: E.g. 80 spm spm.. Cycle time = 0.0125min/stroke or 0.75sec/stroke Year to depreciate, e.g. 7 years RM/yr: RM/month: RM/day: RM/hr: RM/min: RM per 0.0125min or RM per stroke:
Heat treatment § RM / kg rate § RM for special requirement § Material § Heat treatment method § Electrical furnace § Induction § Process control
Handling cost § Machine setting § Assembly and dismantling § Quality control § Progress control § Storage § RM/hr
Delivery § Transportation mode § § § § §
Lorry or car or motorcycle (depreciation) Driver Petrol Maintenance (tyre (tyre wear, engine oil, etc) Toll
§ RM / km § Weight category , e.g. § Less than 150 kg at RM1/kg § Others at RM2/kg § Size or volume category
Administration cost
§ Apportionment: % to be budgeted on capital expenditure, e.g. supporting machines, furniture, forklift, etc § RM/hr § Eg Eg.. § Admin staff payroll: Total RM50,000 per month § Power & utility: RM5,000 per month § Building depreciation or rentals: RM10,000 month § 2 shifts, 8 hours / shift, 22 days / month. Equals to 352 hours / month
Administration cost § Admin cost / month: RM65,000 § Rate: RM65,000 / 352 hours § RM185 / hr § For e.g. 50 projects per year. Apportionment equals 1/50. or RM3.70 / hr / project
Profit margin § % of total production cost § % value depends on: § Difficulty level § Timeline given by customer § Wisdom: § Can others do it? § Rule of thumb
Quotation to customer § Project name § Project reference number § Price § Warranty § Delivery date
Amortisation § Definitions (ref: Wikipedia) § of capital expenditures of certain assets under accounting rules, particularly intangible assets,, in a manner analogous to depreciation assets § is the distribution of a single lump lump--sum cash flow into many smaller cash flow installments, as determined by an amortization schedule
§ E.g. soft tools, R&D, prototype
Cost summary Item
Basis
Rate (e.g.)
Design
Hrs
RM25/hr
Raw material
Kg
RM7/kg
Std. part
L/s
As manufacturer list
Machining
Hrs
RM5 to RM60/hr
Heat treatment
Kg
RM5/kg
Handling
Hrs
RM5/hr
Delivery
Km, weight, volume
RM5 to RM60/km
Admin
Hrs
RM4
Total
-
Profit margin
%
Quotation
50 to 200
RM
Cost summary
Tue 09 Mar 2010
Forming technologies § Forming automation § High Speed Forming Machine § Fineblanking
Yamada Omega: 3,000RPM
Fineblanking: 300 pcs/min Forming machine with auto-feeder
Design samples
Special designs Sensors in die
Ball catch
Strip utilization
§ Utilization rate of strip in producing the workpiece flat blank § Determines a good design or otherwise § To determine the best configuration § Nr of row § Straight or slanting layout
Strip utilization § Calculation: § § § § §
Ŋ = Utilization efficiency (%) R = Nr of row A = flat blank surface area (inclusive holes) V = Strip pitch B = Strip width
R.A η= V.B
Force centre point § U = perimeter of each punch § a = distance of punch centre point to a reference point § x = distance between force centre point to reference point
U1.a1 + U 2 .a2 + U 3 .a3 + ... x= U1 + U 2 + U 3 + ...
