(Adds comments from companies, details of expansion plans)
By John Miller and Paul Arnold
ZURICH, March 12 (Reuters) - Swiss sensors maker Sensirion Holding AG and medical devices group Medartis Holding AG on Monday revealed the price ranges for their stock market debuts, joining a rush of companies listing on the Swiss bourse.
The first half of 2018 is shaping up to be the busiest for Swiss initial public offerings since at least 2014, when five companies listed.
Sensirion, whose sensors go into cars, mobile phones, hospitals and petrochemicals plants, set a price range of 28 to 36 Swiss francs per share, potentially valuing the company at about 560 million Swiss francs. It plans to sell 9.3 million shares in the offering and its order books were already covered, including a so-called greenshoe, within hours, one of the bookrunners on the deal said.
Majority shareholder Gottlieb Knoch, a chemist who owns 55 percent of Sensirion, could reap more than 220 million Swiss francs ($232.7 million) for unloading some 6.2 million shares, while retaining a 5.4 percent stake.
Sensirion is also offering nearly 2 million new shares as it aims to raise around 55 million francs to fuel growth.
"We see ourselves as a growth company, not a dividend company," said Moritz Lechner, who with Felix Mayer co-founded Sensirion in 2009. Mayer and Lechner will keep their shares.
Sensirion generated 2017 revenue of 148 million francs and adjusted earnings before interest, depreciation and amortisation (EBITDA) of 26 million. It forecasts revenue growth of 15-18 percent and an adjusted EBITDA margin of 15-16 this year.
Credit Suisse and J.P. Morgan are joint global coordinators and joint bookrunners, with Vontobel a co-bookrunner. Lazard is acting as financial adviser and Homburger AG as legal adviser.
Trading is set to start on March 22.
Meanwhile, Medartis set its price range at 44 to 54 francs per share, valuing the medical devices group at about 650 million francs. The company is selling 2.84 million new shares are could raise as much as 142.5 million francs, including a 15 percent over-allotment option.
Chairman Thomas Straumann, a billionaire who is also a main shareholder in dental implants maker Straumann, will keep all his holdings Medartis.
Medartis said it would to plough the cash into expansion in markets including the United States and Australia, where its products command higher prices than in Europe.
"We will expand massively in the United States, that's an interesting and large market," Chief Financial Officer Dominique Leutwyler said. Germany, China and Japan are also expansion prospects.
Medartis, whose shares are due to begin trading on March 23, generated 105 million francs in 2017 sales, up 14 percent from a year earlier, and EBITDA of 19 million.
It give no detailed growth forecasts, but Straumann told reporters the $8 billion market for hand, wrist, foot, ankle and jaw implants was expanding at about 6 percent annually -- about twice that of devices for spine, knee and hip surgeries.
Zuercher Kantonalbank and Bryan, Garnier & Co are joint global coordinators and joint bookrunners for Medartis, while Kepler Cheuvreux is acting as co-manager. Quarton International is acting as financial adviser.
Other companies lining up to float in Switzerland include Chinese conglomerate HNA Group, which is listing airline caterer Gategroup as it raises funds to slash debt . HNA's ground services and cargo handling unit Swissport is also set to go public.
Private social network operator ASMALLWORLD AG plans to list on the SIX Swiss Exchange without selling new shares.
$1 = 0.9499 Swiss francs Additional reporting by Michael Shields. Editing by Jane Merriman