Weiter zum Inhalt
UB der TUM
OPAC
Universitätsbibliothek
Technische Universität München
  • Temporäre Merkliste: 0 temporär gemerkt (Voll)
  • Hilfe
    • Kontakt
    • Suchtipps
    • Informationen Fernleihe
  • Chat
  • Tools
    • Suchhistorie
    • Freie Fernleihe
    • Erwerbungsvorschlag
  • English
  • Konto

    Konto

    • Ausgeliehen
    • Bestellt
    • Sperren/Gebühren
    • Profil
    • Suchhistorie
  • Log out
  • Login
  • Bücher & Journals
  • Papers
Erweitert
  • Lean for the process industrie...
  • Zitieren
  • Als E-Mail versenden
  • Drucken
  • Datensatz exportieren
    • Exportieren nach RefWorks
    • Exportieren nach EndNoteWeb
    • Exportieren nach EndNote
    • Exportieren nach BibTeX
    • Exportieren nach RIS
  • Zur Merkliste hinzufügen
  • Temporär merken Aus der temporären Merkliste entfernen
  • Permalink
Export abgeschlossen — 
Buchumschlag
Gespeichert in:
Bibliographische Detailangaben
Beteilige Person: King, Peter L. (VerfasserIn)
Format: Buch
Sprache:Englisch
Veröffentlicht: Boca Raton [u.a.] CRC Press 2009
Schlagwörter:
Manufacturing processes
Process control
Verarbeitende Industrie
Lean Production
Links:http://www.loc.gov/catdir/enhancements/fy0916/2008051281-b.html
http://www.loc.gov/catdir/enhancements/fy0916/2008051281-d.html
http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&local_base=BVB01&doc_number=018856661&sequence=000002&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA
Umfang:XXIII, 333 S. graph. Darst. 24 cm
ISBN:9781420078510
1420078518
Internformat

MARC

LEADER 00000nam a2200000 c 4500
001 BV035962512
003 DE-604
005 20100208
007 t|
008 100119s2009 xxud||| |||| 00||| eng d
010 |a 2008051281 
020 |a 9781420078510  |9 978-1-4200-7851-0 
020 |a 1420078518  |9 1-420-07851-8 
035 |a (OCoLC)289095889 
035 |a (DE-599)BVBBV035962512 
040 |a DE-604  |b ger  |e aacr 
041 0 |a eng 
044 |a xxu  |c US 
049 |a DE-M347 
050 0 |a TS183 
082 0 |a 658.5 
084 |a QP 500  |0 (DE-625)141894:  |2 rvk 
100 1 |a King, Peter L.  |e Verfasser  |4 aut 
245 1 0 |a Lean for the process industries  |b dealing with complexity  |c Peter L. King 
264 1 |a Boca Raton [u.a.]  |b CRC Press  |c 2009 
300 |a XXIII, 333 S.  |b graph. Darst.  |c 24 cm 
336 |b txt  |2 rdacontent 
337 |b n  |2 rdamedia 
338 |b nc  |2 rdacarrier 
650 4 |a Manufacturing processes 
650 4 |a Process control 
650 0 7 |a Verarbeitende Industrie  |0 (DE-588)4133768-2  |2 gnd  |9 rswk-swf 
650 0 7 |a Lean Production  |0 (DE-588)4287302-2  |2 gnd  |9 rswk-swf 
689 0 0 |a Lean Production  |0 (DE-588)4287302-2  |D s 
689 0 1 |a Verarbeitende Industrie  |0 (DE-588)4133768-2  |D s 
689 0 |5 DE-604 
856 4 |u http://www.loc.gov/catdir/enhancements/fy0916/2008051281-b.html  |3 Contributor biographical information 
856 4 |u http://www.loc.gov/catdir/enhancements/fy0916/2008051281-d.html  |3 Publisher description 
856 4 2 |m HBZ Datenaustausch  |q application/pdf  |u http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&local_base=BVB01&doc_number=018856661&sequence=000002&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA  |3 Inhaltsverzeichnis 
943 1 |a oai:aleph.bib-bvb.de:BVB01-018856661 

Datensatz im Suchindex

_version_ 1819316245211643904
adam_text Titel: Lean for the process industries Autor: King, Peter L. Jahr: 2009 Contents Acknowledgments................................................................................xv Introduction........................................................................................xvii PART I Lean and the Process Industries Chapter 1 Lean Overview: Principles and Tools...............................3 Origins of Lean............................................................................3 TPS Becomes the New Production Paradigm.........................6 Essence of Lean............................................................................8 Fourteen Lean Tools..................................................................11 Lean Tool 1: Value Stream Mapping (VSM).....................11 Lean Tool 2: Takt Time........................................................11 Lean Tool 3: Kaizen..............................................................12 Lean Tool 4: 5S......................................................................12 Lean Tool 5: Jidoka...............................................................12 Lean Tool 6: Single Minute Exchange of Dies (SMED) ....13 Lean Tool 7: Poka-Yoke........................................................13 Lean Tool 8: Five Whys........................................................13 Lean Tool 9: Standard Work...............................................13 Lean Tool 10: Total Productive Maintenance (TPM)......14 Lean Tool 11: Cellular Manufacturing..............................14 Lean Tool 12: Heijunka........................................................14 Lean Tool 13: Just-In-Time (Pull).......................................15 Lean Tool 14: Kanban..........................................................15 Further Information.................................................................15 Lean Today.................................................................................16 Summary....................................................................................17 Chapter 2 Distinguishing Characteristics of Process Industry Manufacturing................................19 Process Industries versus Assembly Operations...................19 vi • Contents Characteristics That Distinguish the Process Industries....................................................................................21 The Three Vs: Volume, Variety, and Variability...............21 Capital Intensive versus Labor Intensive...........................22 Throughput Is Limited by Equipment Rather Than by Labor.................................................................................23 Equipment Is Large and Difficult to Relocate...................24 Processes Are Difficult to Stop and Restart......................24 Product Changeover Issues Are Complex.........................24 Finished Product Inventory versus WIP...........................25 Hidden WIP..........................................................................26 Material Flow Patterns in Assembly and Process Plants (SKU Fan Out)...........................................................26 Examples of V Type Process in Process Plants............28 Product Differentiation Points............................................32 Summary....................................................................................33 Chapter 3 The Seven (or Eight, or Nine) Wastes in the Process Industries............................................................37 Value and Waste........................................................................37 Waste of Overproduction.........................................................38 Waste of Time on Hand (Waiting)........................................40 Waste in Transportation..........................................................42 Waste of Processing Itself........................................................43 Waste of Stock on Hand (Inventory).....................................44 Capacity Differences: Rate Synchronization.....................45 Bottleneck Protection..........................................................46 Campaign Sizes....................................................................46 Inappropriate Product Differentiation.............................46 Tank Heels.............................................................................47 Waste of Movement...................................................................47 Waste of Making Defective Parts...........................................48 Waste of Human Creativity.....................................................49 Time as a Waste.........................................................................50 Necessary versus Unnecessary Waste....................................51 Summary....................................................................................52 Contents • vii PART II Seeing the Waste Chapter 4 Value Stream Mapping the Process Industries..............57 Introduction to Value Stream Mapping.................................57 Benefits of a Value Stream Map...............................................58 Generating the Map..................................................................59 Direction of Flow......................................................................60 Product Families.......................................................................60 Takt and Cycle Time.................................................................61 TaktTime...............................................................................61 Cycle Time.............................................................................62 Takt Rate versus Takt Time.................................................63 Units of Production...................................................................63 Where to Begin.........................................................................66 Level of Detail...........................................................................66 Process Box................................................................................68 Data Boxes..................................................................................69 Customer Data Box..............................................................69 Process Step Data Box..........................................................70 Inventory Data Box..............................................................73 Transportation Data Box.....................................................74 Supplier Data Box.................................................................75 Information Flow......................................................................75 The Timeline..............................................................................78 An Example VSM......................................................................81 Additional VSM Best Practices...............................................81 Parallel Equipment...............................................................81 Logical Flow versus Geographic Arrangement...............84 Summary...................................................................................88 Chapter 5 Reading and Analyzing the Current State Value Stream Map.......................................................................89 Analyzing the Current State Map...........................................89 Voice of the Customer.........................................................90 Waste.....................................................................................90 Non-Value-Adding Activities.............................................91 viii • Contents Flow and Bottlenecks...........................................................91 Variability..............................................................................92 Other Opportunities............................................................92 Learning from Material Flow..................................................93 Learning from Information Flow............................................98 Tools to Get to Root Cause.....................................................101 The Five Whys (5W)...........................................................101 Detailed Process Mapping.................................................102 The Ishikawa Diagram.......................................................102 Cross-Functional Process Mapping.................................102 Creating the Future State VSM..............................................104 Summary..................................................................................107 PART HI Lean Tools Needing Little Modification Chapter 6 Total Productive Maintenance.......................................Ill TPM and Lean Synergy..........................................................112 TPM in the Process Industries..............................................113 TPM and Reliability-Centered Maintenance......................114 The Benefits of TPM................................................................114 TPM Measures.........................................................................114 Overall Equipment Effectiveness......................................115 Availability......................................................................115 Performance...................................................................115 Quality.............................................................................116 UPtime.................................................................................116 Calculation of OEE and UPtime......................................118 Calculation of OEE........................................................118 Calculation of UPtime.................................................120 VSM Data Boxes: OEE or UPtime..................................120 Summary..................................................................................121 Chapter 7 Setup Reduction and SMED..........................................123 SMED and Its Origins...........................................................123 Contents • ix SMED Concepts......................................................................124 Product Transitions in the Process Industries...................126 A Changeover Where All Tasks Are Completely Manual.................................................................................127 A Changeover Completely in Chemistry and/or Physics....................................................................128 A Changeover That Includes a Combination of Manual Tasks and Chemistry/Physics.......................128 SMED beyond Product Changes...........................................130 A Non-Manufacturing Example...........................................131 Summary..................................................................................132 Chapter 8 Visual Management.......................................................135 Introduction to the Visual Plant...........................................135 Visual Work Area....................................................................137 Visual Displays.........................................................................138 Visual Scheduling....................................................................139 Andons......................................................................................144 Metrics......................................................................................144 Management by Sight and Frequent Communication.......145 Process Industry Challenges..................................................145 Summary..................................................................................147 Chapter 9 Kaizen Events.................................................................149 Kaizen by Specific Events.......................................................149 Quality Circles versus Kaizen Events...................................151 Steps in the Kaizen Event Process.........................................151 Planning...............................................................................152 Conducting the Event........................................................153 Following-Up......................................................................154 Appropriate Event Scope Areas............................................154 Kaizen Dangers: The Root Causes of Kaizen Failures.......155 Process Industry Unique Requirements..............................157 Kaizen Events as Six Sigma Projects.....................................158 Summary..................................................................................160 x • Contents PART IV Lean Tools Needing a Different Approach Chapter 10 Finding, Managing, and Improving Bottlenecks.........163 Bottlenecks in Process Plants................................................163 Moving Bottlenecks................................................................165 Recognizing Covert Bottlenecks...........................................167 The Root Causes of Bottlenecks............................................168 Bottleneck Management: Theory of Constraints................171 Widening the Bottleneck: Lurking Bottlenecks..................174 Summary..................................................................................175 Chapter 11 Cellular Manufacturing in the Process Industries......177 The Process Layout (Pre-Cellular Manufacturing in Assembly Plants).................................................................177 The Product Layout (Cellular Manufacturing in Assembly Plants).................................................................178 Cell Application in the Process Industries..........................180 Typical Process Plant Equipment Configurations..............181 Virtual Cells.............................................................................185 Case Study: Virtual Cell Implementation in a Synthetic Rubber Production Facility..............................189 The Result: Synthetic Rubber Virtual Work Cells.........193 Steps in Virtual Work Cell Design........................................195 Step 1: Start with the Current State Value Stream Map ..195 Step 2: Determine Preliminary Asset Groups or Virtual Cells........................................................................196 Step 3: Determine Preliminary Product Groupings (Group Technology)...........................................................196 Step 4: Assign Each Product Group to a Manufacturing Cell.............................................................196 Step 5: Define a Few Swing Products...............................198 Step 6: Review the Plan......................................................198 Step 7: Document Virtual Cell Arrangements, Flow Patterns, Product Lineups, and Operating Rules...........199 Step 8: Mark Each Cell Visually.......................................199 Contents • xi Step 9: Modify Scheduling Processes Accordingly........199 Step 10: Ensure that Appropriate Managing Processes Are in Place........................................................199 Summary..................................................................................201 Chapter 12 Product Wheels: Production Scheduling, Production Sequencing, Production Leveling.............203 Solutions in Assembly Processes..........................................203 Process Industry Challenges.................................................205 A Process Industry Solution: The Product Wheel Concept.................................................206 Product Wheel Design...........................................................209 Step 1: Determine Which Process Steps Should Be Scheduled by Product Wheels..........................................211 Step 2: Analyze Product Demand Variability.................212 Step 3: Determine the Optimum Sequence.....................215 Step 4: Calculate Shortest Wheel Time Possible (Available Time Model).....................................................216 Step 5: Estimate Economic Optimum Wheel Time (the EOQ Model)................................................................217 Step 6: Determine the Wheel Time (Making the Choice)..........................................................219 Step 7: Calculate Inventory Requirements.....................222 Step 8: Fine-Tune the Design............................................224 Step 9: Revise the Current Scheduling Process.............225 Step 10: Create a Visual Display......................................225 Benefits of Product Wheels...................................................226 Some Additional Points.........................................................227 Summary.................................................................................228 Chapter 13 Postponement in the Process Industries: Finish to Order...............................................................229 Finish to Order........................................................................230 Examples of Finish to Order: FTO in Assembly................230 FTO in the Process Industries...............................................232 FTO within Process Plants.....................................................232 xii • Contents The Benefits of FTO................................................................233 Example of FTO in a Process Plant.....................................234 A Further Example: Bond to Order......................................237 Summary.................................................................................240 Chapter 14 Pull Replenishment Systems..........................................241 What Is Pull?............................................................................241 Pull in Assembly.....................................................................243 Difficulties in Process Plants.................................................245 Push-Pull Interface................................................................246 ConWIP...................................................................................250 Development of Pull on the Sheet Goods Process.............254 Visual Signals..........................................................................258 When to Start Pulling: The Sequence of Implementation..................................................................260 Creating Pull............................................................................261 Value Stream Focus................................................................263 Traditional Pull Strategies and Signals...............................265 Push in Real Life.....................................................................266 Summary.................................................................................267 Chapter 15 Supermarket Design.......................................................269 Understanding the Supermarket Concept...........................270 Inventory Types and Supermarkets......................................271 Inventory Components Denned: Cycle Stock and Safety Stock..............................................................................272 Calculating Cycle Stock..........................................................275 Calculating Cycle Stock: Fixed Interval Replenishment Model........................................................275 Calculating Cycle Stock: Fixed Quantity Replenishment Model........................................................278 Calculating Safety Stock.........................................................281 Variability in Demand.......................................................281 Variability in Lead Time...................................................283 Combined Variability........................................................284 Cycle Service Level and Fill Rate.....................................284 Example: The Product Wheel for Forming Machine 1.....286 Contents • xiii Alternatives to Safety Stock..................................................290 Signaling Methods..................................................................291 The Role of Forecasting.........................................................292 Summary..................................................................................293 Chapter 16 The Importance of Leadership and Robust Business Processes.........................................................295 Business Practices and Targets.............................................296 ABC Classification.............................................................296 Customer Lead Times.......................................................297 Customer Service Levels...................................................298 MTS, MTO, and FTO.......................................................298 Demand Variability Analysis...........................................298 Protection (Safety Stock or Contingency Processes).... 299 SKU Rationalization..........................................................299 Integrated Business and Operations Planning..............300 Poor Business Practices.........................................................300 Dictating Low Safety Stock Levels..................................300 Expecting Abnormally Short Lead Times......................300 Expecting Perfect Customer Service................................301 Reducing Inventory at Year End.......................................301 Pulling Next Quarters Sales Ahead.................................301 Obsessing over Cost Reduction.......................................302 Inappropriate Use of Metrics................................................302 Summary.................................................................................303 PART V Appendices Appendix A: Determination of Appropriate Raw Material Inventory..............................................................................307 Appendix B: References.......................................................................311 Index....................................................................................................313 About the Author................................................................................333
any_adam_object 1
author King, Peter L.
author_facet King, Peter L.
author_role aut
author_sort King, Peter L.
author_variant p l k pl plk
building Verbundindex
bvnumber BV035962512
callnumber-first T - Technology
callnumber-label TS183
callnumber-raw TS183
callnumber-search TS183
callnumber-sort TS 3183
callnumber-subject TS - Manufactures
classification_rvk QP 500
ctrlnum (OCoLC)289095889
(DE-599)BVBBV035962512
dewey-full 658.5
dewey-hundreds 600 - Technology (Applied sciences)
dewey-ones 658 - General management
dewey-raw 658.5
dewey-search 658.5
dewey-sort 3658.5
dewey-tens 650 - Management and auxiliary services
discipline Wirtschaftswissenschaften
format Book
fullrecord <?xml version="1.0" encoding="UTF-8"?><collection xmlns="http://www.loc.gov/MARC21/slim"><record><leader>01746nam a2200445 c 4500</leader><controlfield tag="001">BV035962512</controlfield><controlfield tag="003">DE-604</controlfield><controlfield tag="005">20100208 </controlfield><controlfield tag="007">t|</controlfield><controlfield tag="008">100119s2009 xxud||| |||| 00||| eng d</controlfield><datafield tag="010" ind1=" " ind2=" "><subfield code="a">2008051281</subfield></datafield><datafield tag="020" ind1=" " ind2=" "><subfield code="a">9781420078510</subfield><subfield code="9">978-1-4200-7851-0</subfield></datafield><datafield tag="020" ind1=" " ind2=" "><subfield code="a">1420078518</subfield><subfield code="9">1-420-07851-8</subfield></datafield><datafield tag="035" ind1=" " ind2=" "><subfield code="a">(OCoLC)289095889</subfield></datafield><datafield tag="035" ind1=" " ind2=" "><subfield code="a">(DE-599)BVBBV035962512</subfield></datafield><datafield tag="040" ind1=" " ind2=" "><subfield code="a">DE-604</subfield><subfield code="b">ger</subfield><subfield code="e">aacr</subfield></datafield><datafield tag="041" ind1="0" ind2=" "><subfield code="a">eng</subfield></datafield><datafield tag="044" ind1=" " ind2=" "><subfield code="a">xxu</subfield><subfield code="c">US</subfield></datafield><datafield tag="049" ind1=" " ind2=" "><subfield code="a">DE-M347</subfield></datafield><datafield tag="050" ind1=" " ind2="0"><subfield code="a">TS183</subfield></datafield><datafield tag="082" ind1="0" ind2=" "><subfield code="a">658.5</subfield></datafield><datafield tag="084" ind1=" " ind2=" "><subfield code="a">QP 500</subfield><subfield code="0">(DE-625)141894:</subfield><subfield code="2">rvk</subfield></datafield><datafield tag="100" ind1="1" ind2=" "><subfield code="a">King, Peter L.</subfield><subfield code="e">Verfasser</subfield><subfield code="4">aut</subfield></datafield><datafield tag="245" ind1="1" ind2="0"><subfield code="a">Lean for the process industries</subfield><subfield code="b">dealing with complexity</subfield><subfield code="c">Peter L. King</subfield></datafield><datafield tag="264" ind1=" " ind2="1"><subfield code="a">Boca Raton [u.a.]</subfield><subfield code="b">CRC Press</subfield><subfield code="c">2009</subfield></datafield><datafield tag="300" ind1=" " ind2=" "><subfield code="a">XXIII, 333 S.</subfield><subfield code="b">graph. Darst.</subfield><subfield code="c">24 cm</subfield></datafield><datafield tag="336" ind1=" " ind2=" "><subfield code="b">txt</subfield><subfield code="2">rdacontent</subfield></datafield><datafield tag="337" ind1=" " ind2=" "><subfield code="b">n</subfield><subfield code="2">rdamedia</subfield></datafield><datafield tag="338" ind1=" " ind2=" "><subfield code="b">nc</subfield><subfield code="2">rdacarrier</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">Manufacturing processes</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">Process control</subfield></datafield><datafield tag="650" ind1="0" ind2="7"><subfield code="a">Verarbeitende Industrie</subfield><subfield code="0">(DE-588)4133768-2</subfield><subfield code="2">gnd</subfield><subfield code="9">rswk-swf</subfield></datafield><datafield tag="650" ind1="0" ind2="7"><subfield code="a">Lean Production</subfield><subfield code="0">(DE-588)4287302-2</subfield><subfield code="2">gnd</subfield><subfield code="9">rswk-swf</subfield></datafield><datafield tag="689" ind1="0" ind2="0"><subfield code="a">Lean Production</subfield><subfield code="0">(DE-588)4287302-2</subfield><subfield code="D">s</subfield></datafield><datafield tag="689" ind1="0" ind2="1"><subfield code="a">Verarbeitende Industrie</subfield><subfield code="0">(DE-588)4133768-2</subfield><subfield code="D">s</subfield></datafield><datafield tag="689" ind1="0" ind2=" "><subfield code="5">DE-604</subfield></datafield><datafield tag="856" ind1="4" ind2=" "><subfield code="u">http://www.loc.gov/catdir/enhancements/fy0916/2008051281-b.html</subfield><subfield code="3">Contributor biographical information</subfield></datafield><datafield tag="856" ind1="4" ind2=" "><subfield code="u">http://www.loc.gov/catdir/enhancements/fy0916/2008051281-d.html</subfield><subfield code="3">Publisher description</subfield></datafield><datafield tag="856" ind1="4" ind2="2"><subfield code="m">HBZ Datenaustausch</subfield><subfield code="q">application/pdf</subfield><subfield code="u">http://bvbr.bib-bvb.de:8991/F?func=service&amp;doc_library=BVB01&amp;local_base=BVB01&amp;doc_number=018856661&amp;sequence=000002&amp;line_number=0001&amp;func_code=DB_RECORDS&amp;service_type=MEDIA</subfield><subfield code="3">Inhaltsverzeichnis</subfield></datafield><datafield tag="943" ind1="1" ind2=" "><subfield code="a">oai:aleph.bib-bvb.de:BVB01-018856661</subfield></datafield></record></collection>
id DE-604.BV035962512
illustrated Illustrated
indexdate 2024-12-20T14:04:04Z
institution BVB
isbn 9781420078510
1420078518
language English
lccn 2008051281
oai_aleph_id oai:aleph.bib-bvb.de:BVB01-018856661
oclc_num 289095889
open_access_boolean
owner DE-M347
owner_facet DE-M347
physical XXIII, 333 S. graph. Darst. 24 cm
publishDate 2009
publishDateSearch 2009
publishDateSort 2009
publisher CRC Press
record_format marc
spellingShingle King, Peter L.
Lean for the process industries dealing with complexity
Manufacturing processes
Process control
Verarbeitende Industrie (DE-588)4133768-2 gnd
Lean Production (DE-588)4287302-2 gnd
subject_GND (DE-588)4133768-2
(DE-588)4287302-2
title Lean for the process industries dealing with complexity
title_auth Lean for the process industries dealing with complexity
title_exact_search Lean for the process industries dealing with complexity
title_full Lean for the process industries dealing with complexity Peter L. King
title_fullStr Lean for the process industries dealing with complexity Peter L. King
title_full_unstemmed Lean for the process industries dealing with complexity Peter L. King
title_short Lean for the process industries
title_sort lean for the process industries dealing with complexity
title_sub dealing with complexity
topic Manufacturing processes
Process control
Verarbeitende Industrie (DE-588)4133768-2 gnd
Lean Production (DE-588)4287302-2 gnd
topic_facet Manufacturing processes
Process control
Verarbeitende Industrie
Lean Production
url http://www.loc.gov/catdir/enhancements/fy0916/2008051281-b.html
http://www.loc.gov/catdir/enhancements/fy0916/2008051281-d.html
http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&local_base=BVB01&doc_number=018856661&sequence=000002&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA
work_keys_str_mv AT kingpeterl leanfortheprocessindustriesdealingwithcomplexity
  • Verfügbarkeit

‌

Per Fernleihe bestellen Inhaltsverzeichnis
  • Impressum
  • Datenschutz
  • Barrierefreiheit
  • Kontakt