|342 West Creston Rd.|
Crossville, TN 38571
|We can meet your Tool & Die design requirements,email fully detailed designs to your location, or provideyou with a full set of construction drawings. . . . allin the time you could be waiting for your own designdepartment to find the time.|
Time is of the essence!
|Just in time. Yourtoolmakers must receive their drawings with enough timefor construction, tryout and development.|
Having been a Tool& Die Journeyman for almost 25 years, I understandthis and do my utmost to facilitate a shortlead-time.
Designed in dimension control!
|I am experiencedwith the demands and expectations of Statistical ProcessControl and the engineering requirements of Controldimensions.|
|STAT designs:||Progressive Dies, Compound Dies, Form Dies, Welding &Machining fixtures, Gages, Special Machines, Multi-slideTooling.|
STAT helps toolmakers:
|Our designs aretoolmaker friendly and economical to build andmaintain.|
|How much Die do youneed?|
The primary information usually received whenreceiving an RFQ for a stamped part is a part drawingthat specifies the complexity of the part, material,precision requirements and monthly/yearly volumesneeded. The part size, complexity and material specsof course determine the size and complexity of thedie required, so a strip layout is the first beststep in determining tooling costs.The Striplayout
All of the engineering problems involved in stampinga part to print from a strip of coil stock need to beconsidered and solved at this stage. The requiredprecision of the finished stamping must beconsidered, starting with the control dimensions andtight tolerance dimensions on the part that willdictate the operations and their sequence. The striplayout can be done in a 2D drawing but a 3D model isalways more revealing. It helps to visualize exactlywhat the strip layout will look like rather thanhaving to assemble such an image in your mind from 3or more projected 2D views. It is in the strip layoutwhere the part is broken down into a sequence ofoperations ordered in such a way that all featuresand tolerances can be controlled. Once the sequenceof operations is established, idle stations can beinserted where necessary. Once completed, the die setsize, and tonnage requirements can be calculated thatdictates some of the Press requirements.
The questions of dimensional control, the demands ofvolume and precision, and strip control should all beaddressed by the strip layout. Partdimensions that are unrealistic should be addressedwith the aim of a part print revision.
Oncehaving settled upon a stamping process that you aresatisfied with, it is a good idea to give your clientthe opportunity to review the strip layout,suggest improvements and/or sign off on it. And by theway, this is another good reason to present a 3D modelof the strip layout. After all, your client hasn'tbeen staring at these lines for hours like you have,and a 3D model will give your client an immediateapprehension of your concept and how you intend toinsure parts to print.The Die conceptdesign
The concept design stage for me, is a complete 3D dieassembly design, including all screw and dowel holesbecause even the quantity and placement of screws anddowels are an integral part of the design concept.The Die is designed around the strip layout, from theinside out and often times it is something as simpleas needing room for screws and dowels that will forcethe need for an idle station.
Since all of the manufacturing process questions havebeen already addressed in the strip layout, now isthe time to consider the effects of requiredproduction. Does the volume requirement dictate thatthe Die must be designed to be serviceable in thePress? If so, then every working section must bedesigned for easy removal and service. Every punchmust be easily removed for service. If there areheavy stripper plates they will need removablewindows for access to punches, etc.
At this stage in the design process, all thepertinent force calculations need to be done todetermine blanking, stripping and formingpressures. Unequal side thrust forces will have to becounter-balanced because this is not the job of theguide pins in the die set.
Also, at this stage there is the matter ofconsidering the Press that this die will run in. Themain considerations are tonnage, die space, feedheight, shut height and target strokes perminute. The main issues affecting die costs are partsize, material, precision and volume. Part sizejust dictates how big a die will be, but material,precision and volume affect the complexity of the dieand whether or not premium steels and/or treatmentswill be needed.Precision
For high precision dies it may be necessary to guidepunches, which means you may need to guide thestrippers as well. For dimensions that can change asthe stock in the coil changes, it may be necessary tomake location adjustments on the fly. If you haveholes with tight tolerance hole positions affected bybends, it may be necessary to use cam-punches topierce after forming to guarantee dimensionalcontrol.Volume
High volume means high maintenance and/or premiumsmaterials and surface treatments that will stand upto high volume production. Higher volume alsosuggests higher press speed, higher feed rates andthe need for electronic die protection. Stock liftand feed through the die needs special attention andthis is probably one of the most overlookedfeatures of die designs. Every movement of the stockstrip needs to be controlled and accurately registered in location while at the same timeoffering as little resistance to feed movement atpossible. It is popular these days to use gas springsfor everything in a die including stock lift, but gassprings do not have as fast a return rate as coilsprings do and therefore there coil springs aresometimes superior to gas springs in a high speedpress. Also to be considered in a high speed stampingoperation is punch shoe and stripper plateweight. Light materials present less mass toaccelerate and for this reason, aluminum die sets andstripper plates are sometimes preferable. All wearsurfaces in the die should be inserted as well, bothfor ease of mainenance and economy. In a high volumepress tool, in-press replaceable items insure lessdown time.Electronic dieprotection
Pitch sensors, part out sensors, slug pullingsensors, even dimension check sensors can be builtinto a die, but this expense is not usuallyconsidered except when production volume prohibitsdown time. Once upon a time, all that was availablewas a misfeed detection pilot. It was not veryeffective since it could not sense a misfeed and stopthe press before damage was done. Now with the use ofproximity sensors, a misfeed can be detected and thepress stopped while in the up-stroke therebypreventing any damage that might occur in the nextstroke.The finaldesign
I use Solidworks personally for die design. Thismeans that by the time I have completed and revisedmy concept design, I have a complete solid model diedesign. Hence, all that is needed is to generate the2D drawings, add dimensions, notes, and a bill ofmaterials. Furthermore, since the design wascompleted as a 3D assembly model, I have every detailin the die available as it's own 3D model that can beimported directly into CNC programming software formachining.
No die design can be adequately documented with paperdrawings anymore. These are essential fordocumentation, but for producing the die componentsthat do the work, 3D models have becomeessential. Often I am asked just to send the paperdrawings in pdf format and the solid models in someother usable format, usually parasolid, step origes. I am sometimes asked for dxf formatted drawingsbut this is rare anymore.Revisions
There are always updates and/or revisions. Any preor post-construction changes should be made on theoriginal 3D assembly model. If this is donecorrectly, all of these changes will automaticallyupdate the 2D drawing files and the 3D componentmodels. This is so important that I offer FREEupdates on all my designs. It is just always truethat when the die construction and development is inprocess that changes are made, either to facilitatemanufacture or to improve the tool. There will beupdates, and these should be incorporated into theoriginal die design. The die design you have in yourfile should be true to the die you have in yourpress. Sadly, and to the chagrin of your toolroom,this is too often neglected.Finalthoughts
Machine tool design should always be a team effort. People from the engineering dept., toolroom, andpressroom should be involved in every designproject. A company should know that it will cost lessin the end if they do not rely on the expertise ofjust one person to design a machine tool that theyare going to have to live with for a long time.
There should be a team review of the strip layoutbefore the die concept design is started. Thereshould be a thorough team review of the die conceptdesign where every party has the opportunity toreview the design individually to make notes, beforethe team review meeting. This review can be doneonline. Webex or Netmeeting have made it possible tohave an effective design review meetingonline. Finally, there should be one more reviewafter the final design is delivered because this isthe first time they will have seen the bill ofmaterials. There are often issues with purchase itemselections or sources that should be addressed atthis time.
Finally, every company should have their own set ofdesign standards. Every company has their preferencesand toolroom standards and these should be written,kept up to date, and in the hands of your designteam. The bottom line is always the issue, and themore problems resolved at the design stage of anyproject is going to result in less cost and moreprofit.
Designs in Solidworks and/or AutoCad!
Call 931-456-6685 or fax 931-456-9538 your RFQ today!